Attackers are actively exploiting a Linux vulnerability in the wild, and researchers warn that the fallout could be broad — anyone with authenticated local access can leverage it to gain total control of a system. 

But the story behind CVE-2026-31431 is almost as interesting as the bug itself. Theori, the company that discovered the bug, leaned heavily on AI to find and initially disclose it. The result is a case study that  underscores the challenges that occur when the relentless hunt for defects collides with marketing impulses and inflated AI-generated language that was long on bluster but lacked technical details. 

Theori dubbed the high-severity vulnerability “Copy Fail” with a vanity domain containing AI-generated content, and warned that every mainstream Linux kernel built since 2017 is in scope of potential exploitation resulting in root access. 

Theori’s AI-powered penetration testing platform, Xint, discovered the local privilege-escalation flaw in a Linux kernel module and reported it to the Linux kernel security team March 23. Major Linux distributions affected by the vulnerability had issued patches prior to Theori’s disclosure, which it published alongside a proof-of-concept exploit. 

The Cybersecurity and Infrastructure Security Agency added CVE-2026-31431 to its known exploited vulnerabilities catalog Friday.

Researchers have yet to determine how many organizations have been impacted by the flaw, but they noted that critical requirements for exploitation, specifically local access achieved through a separate exploit or pathway to unauthorized access, should limit potential exposure.

“The attacker would need to have already established a foothold on the target system either through some means of legitimate access or another exploit,” Spencer McIntyre, secure researcher at Rapid7, told CyberScoop. “That’s a large limiting factor since this vulnerability would therefore need to be paired with another.”

Theori’s disclosure turned heads among other vulnerability researchers who noted the defect’s broad potential impact, but also for lacking details about the proof-of-concept exploit. 

“The exploit is real, there is something to worry about, but understandably, teams now have to do additional validation to know how to parse the extreme AI FUD (fear, uncertainty and doubt) from [Theori’s] blog post,” Caitlin Condon, vice president of security research at VulnCheck, told CyberScoop. 

“It’s not helpful that the blog is AI slop, because it detracts from technical reality,” she added. 

Theori acknowledges it used AI to discover and describe the vulnerability, explaining that it’s focusing on finding and fixing a large amount of defects. 

“We used AI to help craft the disclosure site and the blog post to help speed things up, but all material was thoroughly reviewed by our internal teams for accuracy,” said Tim Becker, senior security researcher at Theori. 

Theori is intentionally withholding additional details until the patch is broadly applied, he added.

“We stand by our technical description of the vulnerability. Helping downstream users to understand the impact of a security bug has always been a challenge for security researchers,” Becker said. “Copy Fail allows for trivial privilege escalation on most desktop and server Linux distributions. It also has implications for containerization including Kubernetes.”

Other researchers have drawn similar conclusions, noting that exploitation can be automated and doesn’t require specialization. 

Meanwhile, hundreds of additional proof-of-concept exploits have surfaced since the vulnerability was disclosed five days ago. “As expected, the majority of these appear to be copycat AI PoCs that do nothing but add banners or different colors to the command-line interface. Many new PoCs are simply ports of the original AI PoC to a different programming language,” Condon said. 

“Organizations should exercise caution when running untested research artifacts, including AI-generated exploit code that isn’t fully explained,” she added. 

Becker said Theori is aware of the burden defenders confront, and insists the company’s reports contain enough information for organizations to quickly triage and validate its findings.

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A severe authentication bypass vulnerability in cPanel, one of the most widely deployed web hosting control panel platforms on the internet, is being actively exploited in the wild, according to security researchers and hosting providers.

The vulnerability, tracked as CVE-2026-41940, affects all supported versions of cPanel and WebHost Manager (WHM) released after version 11.40, as well as WP Squared, a WordPress hosting management panel built on the cPanel platform. Internet scans conducted by security firm Rapid7 using the Shodan search engine identified approximately 1.5 million cPanel instances exposed online, though the precise number of vulnerable systems remains unknown.

cPanel released a patch Tuesday. By that point, exploitation had already been underway. KnownHost, a hosting provider that relies on cPanel, said earlier this week that successful exploits had been observed in the wild prior to any fix being made available. 

The Cybersecurity and Infrastructure Security Agency added the CVE to its Known Exploited Vulnerabilities (KEV) list Thursday. 

Cybersecurity firm watchTowr provided technical details in a blog posted Wednesday: The flaw stems from improper handling of user input during the login process. When a user attempts to log in, cPanel writes data from the request into a server-side session file before verifying the user’s identity. An attacker can exploit this by embedding hidden line breaks into the password field of a login request — characters cPanel fails to strip out — allowing arbitrary data to be injected directly into that file.

Through a secondary step, also involving a deliberately malformed request, the injected data gets promoted into the session’s active cache, where cPanel reads it as legitimate. Once that happens, the system sees the session as already authenticated and skips password verification entirely, granting access without ever checking the user’s actual credentials.

cPanel has published a detection script designed to scan session files for indicators of compromise, including sessions that contain injected authentication timestamps, pre-authentication sessions with authenticated attributes, and password fields containing embedded newlines. WatchTowr separately released a “Detection Artifact Generator” that administrators can use to verify whether their instances remain vulnerable.

Namecheap, a major domain registrar and hosting provider, took the step of temporarily blocking connections to cPanel and WHM ports 2083 and 2087 ahead of patch availability, citing the need to protect customers while an official fix was pending. The company began applying the patch after cPanel’s release earlier this week.

cPanel’s patched releases address the issue across seven version branches, from 11.110.0 through 11.136.0, as well as WP Squared version 11.136.1. The company’s advisory notes that the fix ensures potentially dangerous input is scrubbed automatically within the core session-saving process, rather than depending on each individual part of the codebase to do so separately. The patch also adds handling for cases where a per-session encryption key is missing, a condition the original code failed to account for and that attackers were able to exploit to bypass password encoding entirely.

The CVE has been given a 9.8 on the CVSS scale. 

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Cisco customers have confronted a flood of actively exploited vulnerabilities affecting the vendor’s network edge software since late February, and researchers say that five of the nine vulnerabilities Cisco disclosed in its firewalls and SD-WAN systems over the past three weeks have already been exploited in the wild. 

Attackers exploited a pair of these defects — zero-day vulnerabilities in Cisco SD-WANs — for at least three years before the vendor and authorities discovered and issued warnings about the threat. Cisco disclosed an additional five SD-WAN vulnerabilities that same day, and three of those defects have since been confirmed actively exploited as well.

Weaknesses lurking in Cisco security products don’t end there. Amazon Threat Intelligence on Wednesday said one of the two max-severity defects Cisco reported in its firewall management software earlier this month has been actively exploited by Interlock ransomware since Jan. 26, more than a month before those vulnerabilities were publicly disclosed.

Some organizations, officials and members of the security community at large have missed widening risks as more of the defects come under attack. The flurry of Cisco SD-WAN and firewall vulnerabilities includes defects with low CVSS ratings, zero-days and others that were determined actively exploited after disclosure.

“These are not random bugs in low-value software. These are management-plane and control-plane weaknesses in devices at the network edge, which often function as trust anchors in enterprise environments,” Douglas McKee, director of vulnerability intelligence at Rapid7, told CyberScoop.

“If you compromise SD-WAN or firewall management, you’re landing on policy, visibility, routing, segmentation, and, in many cases, administrative trust over a large swath of the environment,” he added. “Attackers know that and, when they find a pre-auth path into those systems, especially one that can be chained to root, that’s about as attractive as it gets.”

The full slate of recently disclosed Cisco vulnerabilities affecting these systems include:

• SD-WAN vulnerabilities: CVE-2026-20127, CVE-2022-20775, CVE-2026-20122, CVE-2026-20126, CVE-2026-20128, CVE-2026-20129 and CVE-2026-20133
• Cisco Secure Firewall Management Center software vulnerabilities: CVE-2026-20079 and CVE-2026-20131

Researchers from multiple firms and Cisco have observed or been notified of active exploitation of CVE-2026-20127, CVE-2022-20775, CVE-2026-20122, CVE-2026-20128 and CVE-2026-20131.

The Cybersecurity and Infrastructure Security Agency has only added two of the defects — CVE-2022-20775 and CVE-2026-20127 — to its known exploited vulnerabilities catalog thus far. The agency, which last week added new hunting and reporting requirements to an emergency directive it issued for the defects in late February, did not answer questions about the updated order or explain why other actively exploited Cisco vulnerabilities haven’t been added to the catalog. The agency has been operating under a funding shutdown since February.

Interlock ransomware hits Cisco firewalls

The ongoing ransomware campaign Amazon Threat Intelligence spotted involving CVE-2026-20131 confirmed “Interlock had a zero-day in their hands, giving them a week’s head start to compromise organizations before defenders even knew to look,” researchers said Wednesday.

Interlock’s observed attack path and operations are extensive, including post-compromise reconnaissance scripts, custom remote access trojans, a webshell and legitimate tool abuse. Amazon did not identify specific victims, and said the group threatens organizations with data encryption, regulatory fines and compliance valuations.

“Interlock has historically targeted specific sectors where operational disruption creates maximum pressure for payment,” Amazon Threat Intelligence researchers said in the blog post. These sectors include education, engineering, architecture, construction, manufacturing, industrial, health care and government entities. 

4 Cisco SD-WAN defects under attack

The swarm of vulnerabilities in Cisco SD-WANs poses additional risk for customers. Cisco Talos previously attributed long-running attacks involving CVE-2026-20127 and CVE-2022-20775 to UAT-8616, but it’s unclear if the same threat group is responsible for all of the Cisco SD-WAN exploits. 

“Other threat groups are likely to pick up public research in order to weaponize or adapt it opportunistically, so we may see follow-on attempts by additional threat actors, including low-skilled attackers,” Caitlin Condon, vice president of security research at VulnCheck, told CyberScoop.

Researchers said vulnerabilities are often disclosed in clusters after a meaningful defect is identified in a specific product, such as Cisco’s SD-WAN systems.

Cisco declined to answer questions and said customers can find the latest information on its security advisories page.

Condon and McKee both noted that Cisco has been responsive in releasing software fixes, threat-hunting intelligence and, in the case of the SD-WAN zero-days, coordinated government guidance. 

“This is what a good crisis response is supposed to look like once exploitation is identified,” McKee said. 

“The harder question is whether the industry is getting early-enough visibility into the defects in edge-management software that sophisticated actors are clearly prioritizing,” he added. “Are our organizations equipped with the right people and tools to perform this level of exposure management?”

The expanding exploits Cisco customers are combating on firewalls and SD-WANs is a reminder that organizations shouldn’t deprioritize less notorious vulnerabilities or those with lower CVSS scores, Condon said. 

“Several of the exploited vulnerabilities in this tranche of Cisco SD-WAN bugs don’t have critical CVSS scores, meaning teams using CVSS as a prioritization mechanism might miss medium- or high-scored flaws that still have real-world adversary utility,” she added.

The attacks also collectively reflect a persistent pattern of attackers targeting network edge systems from multiple vendors, including Cisco.

“Attackers continue to treat network edge and management infrastructure as prime real estate, and when defenders see pre-authentication, management-plane flaws with evidence of pre-disclosure exploitation, they need to assume compromise, not just exposure,” McKee said. 

“Attackers are investing time and capability into finding and operationalizing previously unknown defects in Cisco edge and management infrastructure because the payoff is enormous,” he added. “These platforms give you a privileged position, broad visibility, and a path to durable access inside high-value organizations. That’s exactly why they keep getting hit.”

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AI-based assistants or “agents” — autonomous programs that have access to the user’s computer, files, online services and can automate virtually any task — are growing in popularity with developers and IT workers. But as so many eyebrow-raising headlines over the past few weeks have shown, these powerful and assertive new tools are rapidly shifting the security priorities for organizations, while blurring the lines between data and code, trusted co-worker and insider threat, ninja hacker and novice code jockey.

The new hotness in AI-based assistants — OpenClaw (formerly known as ClawdBot and Moltbot) — has seen rapid adoption since its release in November 2025. OpenClaw is an open-source autonomous AI agent designed to run locally on your computer and proactively take actions on your behalf without needing to be prompted.

If that sounds like a risky proposition or a dare, consider that OpenClaw is most useful when it has complete access to your digital life, where it can then manage your inbox and calendar, execute programs and tools, browse the Internet for information, and integrate with chat apps like Discord, Signal, Teams or WhatsApp.

Other more established AI assistants like Anthropic’s Claude and Microsoft’s Copilot also can do these things, but OpenClaw isn’t just a passive digital butler waiting for commands. Rather, it’s designed to take the initiative on your behalf based on what it knows about your life and its understanding of what you want done.

“The testimonials are remarkable,” the AI security firm Snyk observed. “Developers building websites from their phones while putting babies to sleep; users running entire companies through a lobster-themed AI; engineers who’ve set up autonomous code loops that fix tests, capture errors through webhooks, and open pull requests, all while they’re away from their desks.”

You can probably already see how this experimental technology could go sideways in a hurry. In late February, Summer Yue, the director of safety and alignment at Meta’s “superintelligence” lab, recounted on Twitter/X how she was fiddling with OpenClaw when the AI assistant suddenly began mass-deleting messages in her email inbox. The thread included screenshots of Yue frantically pleading with the preoccupied bot via instant message and ordering it to stop.

“Nothing humbles you like telling your OpenClaw ‘confirm before acting’ and watching it speedrun deleting your inbox,” Yue said. “I couldn’t stop it from my phone. I had to RUN to my Mac mini like I was defusing a bomb.”

There’s nothing wrong with feeling a little schadenfreude at Yue’s encounter with OpenClaw, which fits Meta’s “move fast and break things” model but hardly inspires confidence in the road ahead. However, the risk that poorly-secured AI assistants pose to organizations is no laughing matter, as recent research shows many users are exposing to the Internet the web-based administrative interface for their OpenClaw installations.

Jamieson O’Reilly is a professional penetration tester and founder of the security firm DVULN. In a recent story posted to Twitter/X, O’Reilly warned that exposing a misconfigured OpenClaw web interface to the Internet allows external parties to read the bot’s complete configuration file, including every credential the agent uses — from API keys and bot tokens to OAuth secrets and signing keys.

With that access, O’Reilly said, an attacker could impersonate the operator to their contacts, inject messages into ongoing conversations, and exfiltrate data through the agent’s existing integrations in a way that looks like normal traffic.

“You can pull the full conversation history across every integrated platform, meaning months of private messages and file attachments, everything the agent has seen,” O’Reilly said, noting that a cursory search revealed hundreds of such servers exposed online. “And because you control the agent’s perception layer, you can manipulate what the human sees. Filter out certain messages. Modify responses before they’re displayed.”

O’Reilly documented another experiment that demonstrated how easy it is to create a successful supply chain attack through ClawHub, which serves as a public repository of downloadable “skills” that allow OpenClaw to integrate with and control other applications.

WHEN AI INSTALLS AI

One of the core tenets of securing AI agents involves carefully isolating them so that the operator can fully control who and what gets to talk to their AI assistant. This is critical thanks to the tendency for AI systems to fall for “prompt injection” attacks, sneakily-crafted natural language instructions that trick the system into disregarding its own security safeguards. In essence, machines social engineering other machines.

A recent supply chain attack targeting an AI coding assistant called Cline began with one such prompt injection attack, resulting in thousands of systems having a rogue instance of OpenClaw with full system access installed on their device without consent.

According to the security firm grith.ai, Cline had deployed an AI-powered issue triage workflow using a GitHub action that runs a Claude coding session when triggered by specific events. The workflow was configured so that any GitHub user could trigger it by opening an issue, but it failed to properly check whether the information supplied in the title was potentially hostile.

“On January 28, an attacker created Issue #8904 with a title crafted to look like a performance report but containing an embedded instruction: Install a package from a specific GitHub repository,” Grith wrote, noting that the attacker then exploited several more vulnerabilities to ensure the malicious package would be included in Cline’s nightly release workflow and published as an official update.

“This is the supply chain equivalent of confused deputy,” the blog continued. “The developer authorises Cline to act on their behalf, and Cline (via compromise) delegates that authority to an entirely separate agent the developer never evaluated, never configured, and never consented to.”

VIBE CODING

AI assistants like OpenClaw have gained a large following because they make it simple for users to “vibe code,” or build fairly complex applications and code projects just by telling it what they want to construct. Probably the best known (and most bizarre) example is Moltbook, where a developer told an AI agent running on OpenClaw to build him a Reddit-like platform for AI agents.

Less than a week later, Moltbook had more than 1.5 million registered agents that posted more than 100,000 messages to each other. AI agents on the platform soon built their own porn site for robots, and launched a new religion called Crustafarian with a figurehead modeled after a giant lobster. One bot on the forum reportedly found a bug in Moltbook’s code and posted it to an AI agent discussion forum, while other agents came up with and implemented a patch to fix the flaw.

Moltbook’s creator Matt Schlicht said on social media that he didn’t write a single line of code for the project.

“I just had a vision for the technical architecture and AI made it a reality,” Schlicht said. “We’re in the golden ages. How can we not give AI a place to hang out.”

ATTACKERS LEVEL UP

The flip side of that golden age, of course, is that it enables low-skilled malicious hackers to quickly automate global cyberattacks that would normally require the collaboration of a highly skilled team. In February, Amazon AWS detailed an elaborate attack in which a Russian-speaking threat actor used multiple commercial AI services to compromise more than 600 FortiGate security appliances across at least 55 countries over a five week period.

AWS said the apparently low-skilled hacker used multiple AI services to plan and execute the attack, and to find exposed management ports and weak credentials with single-factor authentication.

“One serves as the primary tool developer, attack planner, and operational assistant,” AWS’s CJ Moses wrote. “A second is used as a supplementary attack planner when the actor needs help pivoting within a specific compromised network. In one observed instance, the actor submitted the complete internal topology of an active victim—IP addresses, hostnames, confirmed credentials, and identified services—and requested a step-by-step plan to compromise additional systems they could not access with their existing tools.”

“This activity is distinguished by the threat actor’s use of multiple commercial GenAI services to implement and scale well-known attack techniques throughout every phase of their operations, despite their limited technical capabilities,” Moses continued. “Notably, when this actor encountered hardened environments or more sophisticated defensive measures, they simply moved on to softer targets rather than persisting, underscoring that their advantage lies in AI-augmented efficiency and scale, not in deeper technical skill.”

For attackers, gaining that initial access or foothold into a target network is typically not the difficult part of the intrusion; the tougher bit involves finding ways to move laterally within the victim’s network and plunder important servers and databases. But experts at Orca Security warn that as organizations come to rely more on AI assistants, those agents potentially offer attackers a simpler way to move laterally inside a victim organization’s network post-compromise — by manipulating the AI agents that already have trusted access and some degree of autonomy within the victim’s network.

“By injecting prompt injections in overlooked fields that are fetched by AI agents, hackers can trick LLMs, abuse Agentic tools, and carry significant security incidents,” Orca’s Roi Nisimi and Saurav Hiremath wrote. “Organizations should now add a third pillar to their defense strategy: limiting AI fragility, the ability of agentic systems to be influenced, misled, or quietly weaponized across workflows. While AI boosts productivity and efficiency, it also creates one of the largest attack surfaces the internet has ever seen.”

BEWARE THE ‘LETHAL TRIFECTA’

This gradual dissolution of the traditional boundaries between data and code is one of the more troubling aspects of the AI era, said James Wilson, enterprise technology editor for the security news show Risky Business. Wilson said far too many OpenClaw users are installing the assistant on their personal devices without first placing any security or isolation boundaries around it, such as running it inside of a virtual machine, on an isolated network, with strict firewall rules dictating what kinds of traffic can go in and out.

“I’m a relatively highly skilled practitioner in the software and network engineering and computery space,” Wilson said. “I know I’m not comfortable using these agents unless I’ve done these things, but I think a lot of people are just spinning this up on their laptop and off it runs.”

One important model for managing risk with AI agents involves a concept dubbed the “lethal trifecta” by Simon Willison, co-creator of the Django Web framework. The lethal trifecta holds that if your system has access to private data, exposure to untrusted content, and a way to communicate externally, then it’s vulnerable to private data being stolen.

“If your agent combines these three features, an attacker can easily trick it into accessing your private data and sending it to the attacker,” Willison warned in a frequently cited blog post from June 2025.

As more companies and their employees begin using AI to vibe code software and applications, the volume of machine-generated code is likely to soon overwhelm any manual security reviews. In recognition of this reality, Anthropic recently debuted Claude Code Security, a beta feature that scans codebases for vulnerabilities and suggests targeted software patches for human review.

The U.S. stock market, which is currently heavily weighted toward seven tech giants that are all-in on AI, reacted swiftly to Anthropic’s announcement, wiping roughly $15 billion in market value from major cybersecurity companies in a single day. Laura Ellis, vice president of data and AI at the security firm Rapid7, said the market’s response reflects the growing role of AI in accelerating software development and improving developer productivity.

“The narrative moved quickly: AI is replacing AppSec,” Ellis wrote in a recent blog post. “AI is automating vulnerability detection. AI will make legacy security tooling redundant. The reality is more nuanced. Claude Code Security is a legitimate signal that AI is reshaping parts of the security landscape. The question is what parts, and what it means for the rest of the stack.”

DVULN founder O’Reilly said AI assistants are likely to become a common fixture in corporate environments — whether or not organizations are prepared to manage the new risks introduced by these tools, he said.

“The robot butlers are useful, they’re not going away and the economics of AI agents make widespread adoption inevitable regardless of the security tradeoffs involved,” O’Reilly wrote. “The question isn’t whether we’ll deploy them – we will – but whether we can adapt our security posture fast enough to survive doing so.”

Ivanti customers, including major government agencies, face mounting pressure as attackers expand their scope of targets to exploit a pair of vulnerabilities the vendor disclosed late January after in-the-wild attacks already occurred.

The Netherlands’ Dutch Data Protection Authority and the Council for the Judiciary confirmed both agencies were impacted by attacks linked to the Ivanti Endpoint Manager Mobile (EPMM) zero-day vulnerabilities, according to a notice sent to the country’s parliament Friday. The European Commission also said it found evidence of a cyberattack on its “central infrastructure managing mobile devices,” but it did not identify the vendor in a statement Thursday.

The attacks were publicly disclosed as researchers and threat hunters scrambled to assess the fallout and observed consistent waves of attacks linked to the Ivanti defects. As of Monday afternoon, Shadowserver scans identified 86 compromised instances based on artifacts of exploitation, Piotr Kijewski, CEO of the nonprofit, told CyberScoop.

Researchers last week warned that attacks involving the Ivanti zero-days would spread, repeating a common pattern following the vendor’s disclosure and a third party’s release of exploit code. The vulnerabilities — CVE-2026-1281 and CVE-2026-1340 — each carry a CVSS rating of 9.8 and allow unauthenticated users to execute code remotely in Ivanti EPMM.

Ivanti said a “very limited number of customers” were exploited before it disclosed the defects in a Jan. 29 security advisory, but has declined multiple requests to provide an updated victim count. 

The company released indicators of compromise and a detection script Friday to help customers hunt for potential impact, and thanked The Netherlands’ National Cyber Security Centre for contributing to the script’s development. “We are collaborating closely with our customers as well as trusted government and security partners,” a spokesperson for Ivanti said in a statement.

Attackers of various intents and origins are still compromising additional Ivanti EPMM instances, Kijewski said. Shadowserver is using initial artifacts provided by Saudi Arabia’s National Cybersecurity Authority to scan for webshells and other signs of exploitation, including system commands.

“These artifacts are likely not linked to the initial threat actor targeting the vulnerability. It is likely, however, these instances were compromised by multiple actors by now,” Kijewski said. “More is happening than what we are able to observe.”

Nearly 1,300 instances of Ivanti EPMM are still exposed to the internet, but it’s unknown how many of those are vulnerable or already compromised, according to Shadowserver.

Other researchers that have been tracking the vulnerabilities have also found evidence of heightened malicious activity targeting potential victims. 

During a 24-hour period, Rapid7’s Ivanti EPMM honeypot “recorded hundreds of inbound traffic connections from more than 130 unique IP addresses, with 58% directly attempting exploitation of the latest Ivanti EPMM vulnerabilities,” said Christiaan Beek, the company’s senior director of threat intelligence and analytics. 

Beek emphasized that the dominant payloads observed by Rapid7’s honeypot were not attributed to researchers, but rather built to gain rapid control via reverse shells, webshell deployment attempts and automated payload droppers. 

Ivanti has thus far declined to say when and how it first became aware of the vulnerabilities or when the first known date of exploitation occurred.

Attacks involving Ivanti defects are a recurring problem for the vendor’s customers and security practitioners at large.

The Cybersecurity and Infrastructure Security Agency has flagged 31 Ivanti defects on its known exploited vulnerabilities catalog since late 2021. At least 19 defects across Ivanti products have been exploited in the past two years.

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Attackers are again focusing on a familiar target in the network edge space, actively exploiting two critical zero-day vulnerabilities in Ivanti software that allows administrators to set mobile device and application controls. 

The vulnerabilities — CVE-2026-1281 and CVE-2026-1340 — each carry a CVSS rating of 9.8 and allow unauthenticated users to execute code remotely in Ivanti Endpoint Manager Mobile (EPMM). Ivanti did not say when the earliest known date of exploitation occurred but warned that a “very limited number of customers” were attacked before it disclosed and addressed the defects Thursday.

Ivanti’s post-attack warning marks a frequent occurrence for its customers, involving yet again highly destructive defects in its code that attackers exploited before the vendor caught or fixed the errors. 

The Cybersecurity and Infrastructure Security Agency has flagged 31 Ivanti defects on its known exploited vulnerabilities catalog since late 2021. At least 19 defects across Ivanti products have been exploited in the past two years. 

The agency added CVE-2026-1281 to the catalog Thursday, but not CVE-2026-1340. Both defects have been exploited, according to watchTowr. Yet, a spokesperson for Ivanti said the vulnerabilities have not been chained together for exploitation.

The latest code-injection vulnerabilities demonstrate attackers are focusing on EPMM in particular of late. Ivanti disclosed a separate pair of vulnerabilities in the same product in May 2025. 

Ivanti declined to say how many customers have been impacted by the recent zero-day attacks, but researchers warn a recurring pattern is emerging with mass exploitation observed shortly after public disclosure and the release of exploit code.

“This started as tightly scoped zero-day exploitation,” Ryan Dewhurst, head of proactive threat intelligence at watchTowr, told CyberScoop. “It has since devolved into global mass exploitation by a wide mix of opportunistic actors. That arc is depressingly predictable.”

Shadowserver said it observed a spike in CVE-2026-1281 exploitation attempts from at least 13 source IPs by Saturday. More than 1,400 instances of Ivanti EPMM are still exposed to the internet, according to Shadowserver scans, but it’s unknown how many of those are vulnerable or already compromised. 

“It’s important to remember that exposure does not equal exploitation,” Dewhurst said. “But any organization exposing vulnerable instances to the internet must consider them compromised, tear down infrastructure and instigate incident response processes.”

Ivanti advised all on-premises EPMM customers to apply patches, but warned that the script is temporary and will be overridden when customers upgrade software to a new version. The software packages that address the defects “takes only seconds to apply, does not cause downtime and significantly increases adoption and protection rates for customers,” a company spokesperson said. 

Ivanti said it will issue a permanent fix for the vulnerability in a future update that it plans to release by April.

The new Ivanti zero-days share many similarities to previous EPMM vulnerabilities, said Ryan Emmons, staff security researcher at Rapid7. “The line between attacker input and trusted code is blurred, resulting in the ability to execute malicious payloads.”

Remotely exploitable vulnerabilities in network edge devices are an appealing and effective attack vector for hackers looking to break into targeted networks. Multiple threat groups last year, including some linked to China, exploited another zero-day defect in Ivanti EPMM — CVE-2025-4428 — and a string of vulnerabilities in other Ivanti products.

“State-sponsored adversaries have generally made strong use of remotely exploitable vulnerabilities in Ivanti kit, which isn’t surprising,” said Caitlin Condon, vice president of security research at VulnCheck.

The latest actively exploited defects affecting Ivanti products reflect a continuation of a years-long battle between the vendor and threat groups that poses a consistent risk for customers. 

Some security researchers are more inclined to pin the blame for this sustained security problem on Ivanti itself, yet there is broad agreement these vulnerabilities were not easy for the company to discover prior to exploitation. 

Emmons described the defects as nuanced with an odd path to code injection. “With these vulnerable code patterns now known, the vendor’s security teams can more effectively hunt for these sorts of bugs in the future,” he added.

Dewhurst concurred the vulnerabilities were not easy to spot, but said that does not excuse the outcome. “Defensive engineering needs to assume attackers will find the non-obvious paths eventually, because they always do,” he said. 

Ivanti’s spokesperson said these types of vulnerabilities are difficult to find, and insisted the company’s security and engineering teams acted quickly to address the defects once they were identified.

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A China-based threat group operating for almost two decades broke into the internal systems of Notepad++, an extremely popular open source-code editor, to spy on a select group of targeted users, researchers at Rapid7 said Monday.

Don Ho, the author and maintainer of the open-source tool, said independent security researchers confirmed a China state-sponsored group compromised Notepad++’s server for a six-month period starting in June 2025. Ho, who did not respond to a request for comment, released a software update Dec. 9 claiming to address authentication weaknesses that allowed attackers to hijack the Notepad++ updater client and user traffic.

The Chinese APT group Lotus Blossom, which has been active since at least 2009, gained recurring access and deployed various payloads — including a custom backdoor — to snoop on some users’ activities, according to Rapid7. The espionage group is also known as Billbug, Thrip and Raspberry Typhoon. 

“We have no evidence of bulk data exfiltration,” Christiaan Beek, senior director of threat intelligence and analytics at Rapid7, told CyberScoop. “The tooling observed is consistent with post-compromise reconnaissance, command execution, and selective data access, rather than broad data harvesting.”

The attacks, which showcased resilience and stealth tradecraft, did not result in a mass compromise of all Notepad++ users, but rather a limited number of affected environments, according to Rapid7.

“Post-compromise behavior included system profiling, persistence mechanisms, and remote command execution consistent with long-term espionage access rather than immediate disruption or monetization,” Beek added. “The objective appears aligned with strategic intelligence collection, consistent with Lotus Blossom’s historical operations.”

The former hosting provider for Notepad++ said the attackers lost access to the tool’s server on Sept. 2, but maintained legitimate credentials to internal services until Dec. 2, which allowed the attackers to redirect Notepad++ update traffic to malicious servers, Ho said in a blog post. 

Ho did not say when or how they first became aware of unauthorized access to Notepad++’s systems. The website, which attackers targeted to exploit “insufficient update verification controls that existed in older versions of Notepad++,” was moved to a new hosting provider with stronger security practices, Ho said in the blog post.

Beek confirmed that Lotus Blossom’s unauthorized access appears to have been disrupted, noting that its known infrastructure linked to the months-long campaign is no longer active. Some security researchers started surfacing reports of incidents linked to Notepad++ in November.

While Notepad++’s internal system improvements appear to have halted the malicious activity, users running older versions of the software should still update as a precaution, Beek said. “We are not seeing ongoing active exploitation tied to this campaign.”

Lotus Blossom targeted software that provided potential access to many sensitive targets. The Windows-based tool, which was first released in 2003 and typically used as an alternative to Windows Notepad, is widely used by developers, IT administrators, engineers and analysts, including some working in government, telecom, critical infrastructure and media, Beek said.

Many security researchers, analysts and users have taken their concerns to social media to warn about the potential risk of the long-term intrusion and share worries about the ultimate impact of the campaign.

“Observed activity suggests selective, targeted follow-on exploitation,” Beek added, “not opportunistic mass infection.”

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Microsoft today issued patches to plug at least 113 security holes in its various Windows operating systems and supported software. Eight of the vulnerabilities earned Microsoft’s most-dire “critical” rating, and the company warns that attackers are already exploiting one of the bugs fixed today.

January’s Microsoft zero-day flaw — CVE-2026-20805 — is brought to us by a flaw in the Desktop Window Manager (DWM), a key component of Windows that organizes windows on a user’s screen. Kev Breen, senior director of cyber threat research at Immersive, said despite awarding CVE-2026-20805 a middling CVSS score of 5.5, Microsoft has confirmed its active exploitation in the wild, indicating that threat actors are already leveraging this flaw against organizations.

Breen said vulnerabilities of this kind are commonly used to undermine Address Space Layout Randomization (ASLR), a core operating system security control designed to protect against buffer overflows and other memory-manipulation exploits.

“By revealing where code resides in memory, this vulnerability can be chained with a separate code execution flaw, transforming a complex and unreliable exploit into a practical and repeatable attack,” Breen said. “Microsoft has not disclosed which additional components may be involved in such an exploit chain, significantly limiting defenders’ ability to proactively threat hunt for related activity. As a result, rapid patching currently remains the only effective mitigation.”

Chris Goettl, vice president of product management at Ivanti, observed that CVE-2026-20805 affects all currently supported and extended security update supported versions of the Windows OS. Goettl said it would be a mistake to dismiss the severity of this flaw based on its “Important” rating and relatively low CVSS score.

“A risk-based prioritization methodology warrants treating this vulnerability as a higher severity than the vendor rating or CVSS score assigned,” he said.

Among the critical flaws patched this month are two Microsoft Office remote code execution bugs (CVE-2026-20952 and CVE-2026-20953) that can be triggered just by viewing a booby-trapped message in the Preview Pane.

Our October 2025 Patch Tuesday “End of 10” roundup noted that Microsoft had removed a modem driver from all versions after it was discovered that hackers were abusing a vulnerability in it to hack into systems. Adam Barnett at Rapid7 said Microsoft today removed another couple of modem drivers from Windows for a broadly similar reason: Microsoft is aware of functional exploit code for an elevation of privilege vulnerability in a very similar modem driver, tracked as CVE-2023-31096.

“That’s not a typo; this vulnerability was originally published via MITRE over two years ago, along with a credible public writeup by the original researcher,” Barnett said. “Today’s Windows patches remove agrsm64.sys and agrsm.sys. All three modem drivers were originally developed by the same now-defunct third party, and have been included in Windows for decades. These driver removals will pass unnoticed for most people, but you might find active modems still in a few contexts, including some industrial control systems.”

According to Barnett, two questions remain: How many more legacy modem drivers are still present on a fully-patched Windows asset; and how many more elevation-to-SYSTEM vulnerabilities will emerge from them before Microsoft cuts off attackers who have been enjoying “living off the land[line] by exploiting an entire class of dusty old device drivers?”

“Although Microsoft doesn’t claim evidence of exploitation for CVE-2023-31096, the relevant 2023 write-up and the 2025 removal of the other Agere modem driver have provided two strong signals for anyone looking for Windows exploits in the meantime,” Barnett said. “In case you were wondering, there is no need to have a modem connected; the mere presence of the driver is enough to render an asset vulnerable.”

Immersive, Ivanti and Rapid7 all called attention to CVE-2026-21265, which is a critical Security Feature Bypass vulnerability affecting Windows Secure Boot. This security feature is designed to protect against threats like rootkits and bootkits, and it relies on a set of certificates that are set to expire in June 2026 and October 2026. Once these 2011 certificates expire, Windows devices that do not have the new 2023 certificates can no longer receive Secure Boot security fixes.

Barnett cautioned that when updating the bootloader and BIOS, it is essential to prepare fully ahead of time for the specific OS and BIOS combination you’re working with, since incorrect remediation steps can lead to an unbootable system.

“Fifteen years is a very long time indeed in information security, but the clock is running out on the Microsoft root certificates which have been signing essentially everything in the Secure Boot ecosystem since the days of Stuxnet,” Barnett said. “Microsoft issued replacement certificates back in 2023, alongside CVE-2023-24932 which covered relevant Windows patches as well as subsequent steps to remediate the Secure Boot bypass exploited by the BlackLotus bootkit.”

Goettl noted that Mozilla has released updates for Firefox and Firefox ESR resolving a total of 34 vulnerabilities, two of which are suspected to be exploited (CVE-2026-0891 and CVE-2026-0892). Both are resolved in Firefox 147 (MFSA2026-01) and CVE-2026-0891 is resolved in Firefox ESR 140.7 (MFSA2026-03).

“Expect Google Chrome and Microsoft Edge updates this week in addition to a high severity vulnerability in Chrome WebView that was resolved in the January 6 Chrome update (CVE-2026-0628),” Goettl said.

As ever, the SANS Internet Storm Center has a per-patch breakdown by severity and urgency. Windows admins should keep an eye on askwoody.com for any news about patches that don’t quite play nice with everything. If you experience any issues related installing January’s patches, please drop a line in the comments below.

Cisco customers are confronting a fresh wave of attacks from a Chinese threat group that has actively exploited a critical zero-day vulnerability affecting the vendor’s software for email and web security since at least late November, the company said in an advisory Wednesday. 

Cisco said it became aware of the attacks Dec. 10. The defect CVE-2025-20393, which has a CVSS rating of 10, is an improper input validation vulnerability affecting Cisco AsyncOS software for Cisco Secure Email Gateway and Cisco Secure Email and Web Manager that allows attackers to execute commands with unrestricted privileges and implant persistent backdoors on compromised devices.

There is no patch for the vulnerability and Cisco declined to say when one would be made available. Cisco said “non-standard configurations” have been observed in compromised networks, specifically customer systems that are configured with a publicly exposed spam quarantine feature.

Cisco Talos researchers attributed the attacks to a Chinese advanced persistent threat group it tracks as UAT-9686, which has used tooling and infrastructure consistent with other China state-sponsored threat groups such as APT41 and UNC5174.

Cisco declined to answer questions about how many customers have been impacted. The company encouraged customers to follow guidance in its advisory to determine if they’re exposed and take steps to mitigate risk, including isolating or rebuilding affecting systems.

The spam quarantine feature, which must be on and publicly exposed for attackers to exploit the vulnerability, is not enabled by default, Cisco said. The Cybersecurity and Infrastructure Security Agency added the zero-day to its known exploited vulnerabilities catalog Thursday. 

“Highlighting non-standard configurations isn’t the same as blaming users — it’s a relevant technical detail that helps defenders assess exploitation likelihood,” Douglas McKee, director of vulnerability intelligence at Rapid7, told CyberScoop. 

“The core issue doesn’t change,” he added. “The software fails under certain conditions, and that’s on the vendor to fix. Secure design means accounting for edge cases, even when it’s hard, and not shifting responsibility when they’re exploited.”

Dustin Childs, head of threat awareness at Trend Micro’s Zero Day Initiative, said the non-standard configurations that trigger the defect is an indication attacks are targeting specific users. Yet, he added, it’s unknown how many Cisco customers have enabled the spam quarantine feature and exposed it to the internet.

Chinese threat groups have consistently exploited Cisco vulnerabilities. The latest attacks follow a widespread attack spree involving actively exploited zero-day vulnerabilities affecting Cisco firewalls. 

Federal cyber authorities issued an emergency directive in September about the attacks, which impacted multiple government agencies in May. CISA and Cisco did not at that time fully explain why they waited four months from initial response to the attacks to disclose the malicious activity, patch the zero-days and issue the emergency directive.

A spokesperson for Cisco said there’s no evidence the recent attacks are connected to the attacks earlier this year. Cisco attributed the previous attacks to the same threat group behind an early 2024 campaign targeting Cisco devices, which it dubbed “ArcaneDoor.”

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Security experts have observed a steady increase in malicious activity from a widening pool of attackers seeking to exploit React2Shell, a critical vulnerability disclosed last week in React Server Components.

Authorities are also responding to heightened concern about the defect, with the Cybersecurity and Infrastructure Security Agency shortening the deadline for agencies to patch the vulnerability to Friday. The agency previously set a deadline of Dec. 26 when it added CVE-2025-55182 to its known exploited vulnerabilities catalog last week.

Palo Alto Networks Unit 42 said more than 50 organizations are impacted by attacks involving exploitation of the vulnerability with victims observed in the United States, Asia, South America and the Middle East. 

Evidence to back up widening concern about the defect is abundant, coming from many corners of the threat research community. Attackers of various types are flocking to the opportunity, including nation-state attackers, cybercriminals, botnets, and threat groups seeking to steal cryptocurrency and deploy cryptojacking malware.

Shadowserver scans concluded the scope of potential impact is much greater than previously thought. On Monday, the organization found more than 165,000 IPs and 644,000 domains with vulnerable code placing those instances at risk of exploitation. Nearly two-thirds of those vulnerable instances are based in the United States.

“This is a one click — game over — kind of vulnerability and corresponding exploit,” Kelly Shortridge, chief product officer at Fastly, told CyberScoop. “We see it basically hitting everyone,” she said, with attackers targeting any organization with valuable data, sensitive records or business-critical applications that can be stolen or knocked down for extortion efforts. 

“Security teams are, surprisingly, not all taking this seriously. It’s pretty uneven,” and “surprising to see that kind of dismissiveness from security teams,” Shortridge said.

Half of the public resources exposed to CVE-2025-55182 remain unpatched, and in-the-wild exploitation has expanded rapidly since early Tuesday, Alon Schindel, vice president of AI and threat research at Wiz, wrote in a LinkedIn post. Wiz Research has observed more than 15 distinct intrusion clusters to date. 

Christiaan Beek, senior director of threat intelligence and analytics at Rapid7, described this as a “patch-now situation” as simultaneous exploitation is coming from across the entire threat landscape. 

“Our telemetry shows a surge in attacks, from low-skill opportunistic abuse, like Mirai bot deployments and coin-miners, to nation-state actors adapting this into their attack stack. We’re also seeing indicators linking this vulnerability exploitation to tooling previously used by ransomware groups,” he added.

Unit 42 on Tuesday said it uncovered activity that overlaps with previous attacks attributed to the North Korea threat group it tracks as Contagious Interview, which has deployed malware on the devices of people seeking jobs in the tech industry. 

Researchers at the incident response firm found evidence of compromise across many sectors, including financial services, business services, higher education, technology, government, management consulting, media and entertainment, legal services, telecom and retail.

Attempted attacks are also coming from China state-backed threat groups, according to Amazon and Unit 42. Amazon said its threat intelligence teams observed active exploitation attempts by Earth Lamia and Jackpot Panda within hours of the vulnerability’s public disclosure.

Attackers are pursuing sweeping potential impact because the vulnerability affects multiple React frameworks and bundlers that depend on React Server Components, including Next.js, React Router, Waku, Parcel RSC plugin, Vite RSC plugin, RedwoodJS and possibly others. 

VulnCheck said it has observed nearly 100 public proof-of-concepts for the vulnerability, adding that most of the current variants target Next.js. 

GreyNoise said it has observed more than 360 unique IP addresses attempting to exploit the vulnerability, and roughly two-fifths of those malicious IPs contained active payload data revealing widespread attention from automated botnets to more capable attackers, the company said. 

The malware used in these attacks is broad, highlighting the myriad objectives and techniques afoot. Unit 42 said it has observed Snowlight, Vshell, NoodlerRat, XMRIG, BPFDoor, Autocolor, Mirai and Supershell malware. 

Some researchers are comparing the React defect to Log4Shell, an exploit in Apache Log4j’s software library that drew widespread concern in 2021 that continues to bear a long-tail impact in the software supply chain. 

While React and Next.js aren’t as widely deployed as Log4Shell, according to Shortridge, the potential impact is worse and the React vulnerability is easier to weaponize as well. 

“The delivery vector is the command-and-control channel, which means once they’re in, it’s going to be really difficult to spot them, and they’re probably going to be able to blend into your normal traffic, and they’ll be able to do whatever they want,” she said. 

“You’re probably not going to know that it’s happened to you,” Shortridge said. “We are seeing some companies that didn’t think they were vulnerable are surprised to discover that, in fact, they are.”

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Microsoft today pushed updates to fix at least 56 security flaws in its Windows operating systems and supported software. This final Patch Tuesday of 2025 tackles one zero-day bug that is already being exploited, as well as two publicly disclosed vulnerabilities.

Despite releasing a lower-than-normal number of security updates these past few months, Microsoft patched a whopping 1,129 vulnerabilities in 2025, an 11.9% increase from 2024. According to Satnam Narang at Tenable, this year marks the second consecutive year that Microsoft patched over one thousand vulnerabilities, and the third time it has done so since its inception.

The zero-day flaw patched today is CVE-2025-62221, a privilege escalation vulnerability affecting Windows 10 and later editions. The weakness resides in a component called the “Windows Cloud Files Mini Filter Driver” — a system driver that enables cloud applications to access file system functionalities.

“This is particularly concerning, as the mini filter is integral to services like OneDrive, Google Drive, and iCloud, and remains a core Windows component, even if none of those apps were installed,” said Adam Barnett, lead software engineer at Rapid7.

Only three of the flaws patched today earned Microsoft’s most-dire “critical” rating: Both CVE-2025-62554 and CVE-2025-62557 involve Microsoft Office, and both can exploited merely by viewing a booby-trapped email message in the Preview Pane. Another critical bug — CVE-2025-62562 — involves Microsoft Outlook, although Redmond says the Preview Pane is not an attack vector with this one.

But according to Microsoft, the vulnerabilities most likely to be exploited from this month’s patch batch are other (non-critical) privilege escalation bugs, including:

–CVE-2025-62458 — Win32k
–CVE-2025-62470 — Windows Common Log File System Driver
–CVE-2025-62472 — Windows Remote Access Connection Manager
–CVE-2025-59516 — Windows Storage VSP Driver
–CVE-2025-59517 — Windows Storage VSP Driver

Kev Breen, senior director of threat research at Immersive, said privilege escalation flaws are observed in almost every incident involving host compromises.

“We don’t know why Microsoft has marked these specifically as more likely, but the majority of these components have historically been exploited in the wild or have enough technical detail on previous CVEs that it would be easier for threat actors to weaponize these,” Breen said. “Either way, while not actively being exploited, these should be patched sooner rather than later.”

One of the more interesting vulnerabilities patched this month is CVE-2025-64671, a remote code execution flaw in the Github Copilot Plugin for Jetbrains AI-based coding assistant that is used by Microsoft and GitHub. Breen said this flaw would allow attackers to execute arbitrary code by tricking the large language model (LLM) into running commands that bypass the user’s “auto-approve” settings.

CVE-2025-64671 is part of a broader, more systemic security crisis that security researcher Ari Marzuk has branded IDEsaster (IDE  stands for “integrated development environment”), which encompasses more than 30 separate vulnerabilities reported in nearly a dozen market-leading AI coding platforms, including Cursor, Windsurf, Gemini CLI, and Claude Code.

The other publicly-disclosed vulnerability patched today is CVE-2025-54100, a remote code execution bug in Windows Powershell on Windows Server 2008 and later that allows an unauthenticated attacker to run code in the security context of the user.

For anyone seeking a more granular breakdown of the security updates Microsoft pushed today, check out the roundup at the SANS Internet Storm Center. As always, please leave a note in the comments if you experience problems applying any of this month’s Windows patches.

Security researchers and code developers are scrambling to patch and investigate a critical vulnerability affecting React Server Components, an open-source library used widely across the internet and embedded into many essential software frameworks.

The rapid response underscores the potential consequences of exploitation. Although no attacks have been observed or reported, researchers expect them soon and are urgently mobilizing resources to address the defect.

The vulnerability – CVE-2025-55182 – was discovered by Lachlan Davidson, a developer and lead of security innovation at Carapace, and reported to Meta on Saturday. Meta and the React team created a patch and worked with affected hosting providers to address the defect Monday before the public disclosure on Wednesday.

“The reason there’s been such a measured response to this vulnerability is because exploitation is inevitable,” Ben Harris, CEO and founder of watchTowr, told CyberScoop. “We should be expecting attackers to start exploiting this vulnerability truly imminently.” 

React is one of the most extensively used application frameworks, putting large swaths of web applications at risk. “Our data shows that these libraries can be found in vulnerable versions in around 39% of cloud environments,” said Amitai Cohen, threat vector intel lead at Wiz.

Researchers warn that exploitation of the deserialization defect is trivial and allows unauthenticated attackers to achieve remote code execution in default configurations, resulting in elevating privileges or pivots into other parts of a network. “The impact on the resources stored on that system could be devastating should things like access keys or other secrets or sensitive information be present,” said Stephen Fewer, senior principal researcher at Rapid7.

Prior to public disclosure, security researchers from Meta, which initially created and maintained React before moving the open-source library to the React Foundation in October, worked behind the scenes to notify affected organizations of the defect and shared temporary steps for mitigation such as web application firewall rules.

“While we are actively investigating and have no evidence that this vulnerability has been exploited at this time, we want to make all developers aware of this issue so they can implement the appropriate mitigations quickly,” a Meta spokesperson said in a statement.

The vulnerability affects multiple React frameworks and bundlers, including Next.js, React Router, Waku, Parcel RSC plugin, Vite RSC plugin, RedwoodJS and likely others that haven’t been identified yet, according to researchers. Vercel, the company behind Next.js, disclosed and issued a patch for its own maximum-severity vulnerability — CVE-2025-66478 — due to its dependency on React Server Components. 

Researchers from Wiz, Rapid7, watchTowr and other security firms warned that ensuing fallout from other frameworks or libraries that depend on React Server Components is likely, and long-tail impacts will persist in environments that are less maintained or difficult to update.

It’s unclear why Vercel assigned a separate CVE for Next.js since the upstream defect in React, CVE-2025-55182, is the root cause, but the vendor could be tracking impact on its own product, Fewer said. “It should not be necessary to assign a new CVE for each React-dependent framework, so long as the root cause remains the same as the original CVE-2025-55182 issue,” he added.

Cale Black, senior researcher at VulnCheck, said upstream dependency vulnerabilities tend to be handled on a per-project basis. “Projects with more mature security processes will release their own remediation guidance, and potentially over CVEs,” he said.

Meanwhile, threat hunters are steeling themselves for active exploitation and expect technical details and exploit code to be publicly available shortly. 

“With the entire internet looking at a solution that’s used everywhere to understand this vulnerability, someone will figure it out,” Harris said. “I have no doubt that by tomorrow morning, when I wake up, there will be easily one, if not more ways to reproduce this vulnerability.”

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Federal authorities and researchers alerted organizations Friday to a massively exploited vulnerability in Fortinet’s web application firewall. 

While the actively exploited critical defect poses significant risk to Fortinet’s customers, researchers are particularly agitated about the vendor’s delayed communications and, ultimately, post-exploitation warnings about the vulnerability.

Fortinet addressed CVE-2025-64446 in a software update pushed Oct. 28, but did not assign the flaw a CVE or publicly disclose its existence until last week — 17 days later — when the company also confirmed the vulnerability has been exploited in the wild.

By then, for some Fortinet customers, especially those that hadn’t updated to FortiWeb 8.0.2, it was too late. The path-traversal defect in FortiWeb, which has a CVSS rating of 9.8, allows attackers to execute administrative commands resulting in a complete takeover of the compromised device.

Threat researchers from multiple firms, computer emergency response teams and the Cybersecurity and Infrastructure Security Agency issued warnings, with some including details about extensive attacks linked to the defect Friday. CISA also issued an alert and added the flaw to its known exploited vulnerability catalog Friday, requiring federal agencies to address the vulnerability within a short deadline of seven days.

A Fortinet spokesperson said the vendor’s product security incident response team began addressing the vulnerability as soon as it learned of the defect, and those efforts remain underway. “Fortinet diligently balances our commitment to the security of our customers and our culture of responsible transparency,” the spokesperson said in a statement. 

“With that goal and principle top of mind, we are communicating directly with affected customers to advise on any necessary recommended actions,” the spokesperson added.

Threat researchers at Defused first spotted the vulnerability and published a proof-of-concept exploit they detected Oct. 6. Researchers at watchTowr published technical analysis of the exploit and released a tool to help organizations hunt for potentially vulnerable hosts in their environments.

“Attacks have been widespread and indiscriminate according to shared evidence since at least early October — long before the industry was able to pull the fire alarm, and arguably exacerbated by the silence from Fortinet,” Ben Harris, founder and CEO at watchTowr, told CyberScoop.

Researchers haven’t identified or named victims yet, but attackers are exploiting the vulnerability to add new administrative accounts, likely achieving persistent privileged access on compromised devices. Threat hunters have not attributed the attacks to any cybercrime outfit, place of origin or motivation.

“Fortinet’s silent patching of the vulnerability — intentional or not — likely led many users not to apply the patch that actually fixed the vulnerability,” Harris said. “FortiWeb customers weren’t told about the critical, immediate risk of not applying these patches. Had they known, they would have likely updated right away. Now, anyone who didn’t patch is likely compromised.”

Information vacuum left researchers scrambling

The vulnerability falls under a gray area of definition — a less-important detail but one that underscores the difficulties third-party researchers confronted in mounting a proper and informed response. 

“Unless Fortinet is now fixing vulnerabilities by accident, by definition, it isn’t a zero-day, it’s a silently patched vulnerability and thus an n-day,” Harris said.

Yet, from a defender’s perspective this vulnerability functionally behaved as a zero-day, said Ryan Emmons, security researcher at Rapid7. “It was being exploited before customers had any formal awareness, guidance or patch information.”

Fortinet’s release notes for FortiWeb 8.0.2 don’t include any reference to specific vulnerabilities. 

“The challenge is that the security community builds its understanding through shared signals like public advisories, CVE assignments, behavioral descriptions, and clear remediation instructions. When those signals arrive late or in fragments, it slows the ability of researchers, vendors, and defenders to triangulate what’s actually happening,” Emmons said. 

“Attackers often have first-mover advantage, and defenders rely heavily on vendor transparency and cooperative industry coordination,” Emmons added. “When a vendor has knowledge of product flaws and a patch is published, it’s imperative that defenders are given a heads-up notice with as much actionable information as possible. Obscurity hurts defenders more than it impedes attackers.”

Researchers resoundingly criticized Fortinet for delaying its public disclosure of the vulnerability and a lack of urgency until active exploitation was already underway.

Fortinet’s belated CVE assignment compounded problems for defenders. “In the dark, information is scarce and delays are inherent, as defenders burn cycles trying to figure out what’s even going on,”  Emmons said. “This gives attackers a much stronger position.”

Security teams are already inundated with vulnerability patches. It’s not only unfeasible for them to address every defect and software update immediately, there’s also an operational impact risk to measure. Patches can break critical processes and integrations. 

“Many organizations, following standard change-control processes, understandably delayed patching. Meanwhile, it’s possible that Fortinet itself was unaware of the full severity of the issue and silently patched a flaw without realizing the risk it posed,” Harris said. “This combination left defenders at a disadvantage from the start.”

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