Suspected Chinese hackers with a proven knack for exploiting zero-days in security products are at it again, targeting BeyondTrust customers in attacks that researchers have traced back to late August. 

Mandiant researchers said a likely Chinese government-backed espionage group it previously tracked as UNC5221, and now calls Armory Castle, exploited the critical defect — CVE-2026-102764 — then showcased multiple tactics to escalate privileges, hop around the compromised network and evade detection. 

The same threat group has repeatedly exploited a series of defects in Ivanti products since 2023, a Citrix NetScaler zero-day widely known as CitrixBleed, and last year’s Brickstorm campaign that had an average dwell time of 400 days — all resulting in sweeping attack sprees.

“We are aware of only a small number of impacted organizations at this time, but given the stealth of the activity, and the use of a zero-day, it is possible that additional organizations were also compromised prior to the disclosure,” Kelli Vanderlee, senior analyst at Google Threat Intelligence Group, said in an email.

Mandiant warned organizations to “prepare for potential widespread exploitation,” adding that Armory Castle and other threat groups previously conducted broad, opportunistic exploitation following public vulnerability disclosures.

Mandiant and GTIG released their analysis of Armory Castle and its latest campaign as BeyondTrust publicly disclosed the vulnerability in its Remote Support product Thursday. The company’s security said it released a patch for the exploited defect for self-hosted customers Oct. 8 and automatically applied the update to cloud-based versions of the product that same day.

BeyondTrust, which conducted its own investigation and coordinated with Mandiant on an investigation involving a self-hosted customer that was compromised, noted Armory Castle’s prowess.

“This threat actor rotates its infrastructure and tooling for every victim, so attribution here rests on behavior. The indicators from one intrusion rarely survive to the next,” the company’s security team wrote in a blog post. “The threat actor has historically demonstrated a high degree of operational security awareness, professional practices, and tradecraft.”

A BeyondTrust spokesperson declined to answer questions about how many customers are already compromised or why it didn’t publicly disclose the actively exploited zero-day sooner, and instead referred back to its security advisory. 

The company said the first known instance of zero-day exploitation occurred Aug. 29, which it detected and contained Sept. 28. 

BeyondTrust also said it detected the malicious activity after zero-days were confirmed to be exploited in another security vendor’s product Sept. 27. That timing matches a round of zero-days Citrix NetScaler disclosed, following nearly two days of rampant worry and unconfirmed rumors. 

BeyondTrust did not say if there is any link or overlap between the attacks targeting Citrix NetScaler, which went undetected for more than three weeks, and its remote access product. 

GTIG researchers said there isn’t enough evidence to assess an overall targeting trend, but encouraged all potentially vulnerable organizations to apply the patch and hunt for pre-disclosure activity. 

The threat group’s previous targets include business-process outsourcers, government, legal services, technology companies and software-as-a-service providers.

“Armory Castle remains one of the most prominent China-nexus threat actors due to its persistent targeting of various edge device technologies, use of zero-day vulnerabilities for widespread exploitation across multiple industries and regions, and its continuously expanding and evolving arsenal of tools,” said Dan Perez, technical lead at GTIG.

“This is a well-established pattern for Armory Castle,” Vanderlee said. “Targeting edge devices, which typically do not support endpoint detection and response (EDR), allows the threat actor to minimize opportunities for detection and maintain stealthy, persistent access to targeted networks.”

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Microsoft’s streak of record-breaking vulnerability disclosures continued with a mega Patch Tuesday, containing 1,413 defects affecting the company’s various enterprise products and services. 

The monthly batch of patches surpassed the company’s previous annual record of 1,261 common vulnerabilities and exposures (CVEs) set in 2020. 

“Hundreds of CVEs in a single release used to be the exception — now it’s the baseline,” Dustin Childs, head of threat awareness at TrendAI’s Zero Day Initiative, wrote in an email. AI is partly to blame, he added, but it “isn’t creating these bugs out of thin air; it’s just shortening the time between a vulnerability existing and someone noticing it.”

Yet, for defenders understandably overwhelmed by the surge of defects found in Microsoft products, actively exploited zero-day vulnerabilities aren’t growing in kind.

“If there’s solace to be had, it’s in the fact that only one of these bugs is under active attack,” Childs wrote in a blog post. “If you go back to the hot 0-day summer of 2023, there were 17 Microsoft 0-days between January and October as opposed to 15 this year during the same period.”

Microsoft disclosed one actively exploited zero-day affecting Windows Shell — CVE-2026-96951 — that allows unauthorized attackers to bypass a security feature. The high-severity defect is the third Windows Shell vulnerability exploited this year, according to Satnam Narang, senior staff research engineer at Tenable. 

“There have been 26 Windows Shell vulnerabilities patched in 2026 through October, a staggering figure compared to previous years, with only 3 Windows Shell CVEs in 2025 and just one in 2024 and 2022,” he added.

The vast majority of defects Microsoft disclosed in this month’s security update affect Windows, its ubiquitous operating system , spanning 1,102 vulnerabilities combined. The update also included 134 vulnerabilities in Office, 61 in various developer tools and 36 in SharePoint Server. 

Microsoft tried to address the toll this monthly flood of vulnerabilities has on its customers by introducing “risk cohorts.” These groups of vulnerabilities don’t necessarily share a root cause or severity rating, but generally require a similar customer assessment that could guide prioritization efforts, the company said. 

“The volume isn’t the real story anymore,” Childs added. “What matters is that discovery is scaling faster than exploitation, so teams that triage by sheer CVE count instead of exploitability are burning cycles on the wrong bugs. Patch what’s proven, prioritized, and public, and treat everything else as this month’s new normal.”

The full list of vulnerabilities addressed this month is available in Microsoft’s Security Response Center.

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Ivanti customers are in familiar territory, responding to yet another actively exploited zero-day affecting one of the vendor’s most commonly targeted security products. 

Volexity researchers, which discovered in-the-wild exploitation earlier this month, said attackers actually exploited three zero-days in a chain that allowed them to bypass authentication, execute code remotely and escalate privileges. 

Ivanti disclosed and issued a patch for the authentication bypass and remote-code execution components of the exploit chain as a single vulnerability in Ivanti Connect Secure. The company said it initially discovered a portion of the high-severity vulnerability — CVE-2026-104935 — during internal security checks in June.

A threat actor, which Volexity tracks as UTA0576, exploited the defects before Ivanti addressed them and issued a patch.

“Because the issue was discovered internally, was not being actively exploited, and did not meet the threshold for an out-of-band release, a fix was scheduled for inclusion in our normal product release cycle,” an Ivanti spokesperson wrote in response to questions.

“Successful exploitation requires chaining multiple vulnerabilities and Ivanti has fully addressed the unauthenticated remote code execution component of that chain, eliminating the primary exploitation path,” the spokesperson added. “We are also developing additional updates to address the remaining vulnerability and further strengthen product security.”

The full scope of compromise remains under investigation. The company, in a security advisory, said a “limited number of customers” were already compromised prior to disclosure. 

The Cybersecurity and Infrastructure Security Agency added the defect to its known exploited vulnerabilities catalog Tuesday.

Sean Koessel, vice president of professional services at Volexity, said the earliest confirmed instance of exploitation occurred Oct. 1. Yet, “it wouldn’t surprise us if there was activity toward the end of September,” he added.

Volexity researchers observed a series of post-exploitation activities during an investigation involving a customer’s compromised Ivanti Connect Secure VPN appliance earlier this month. “UTA0576 repeatedly exploited these vulnerabilities to compromise the ICS VPN appliance and run commands on it,” the company wrote in a blog post. 

The threat actor extracted credentials stored on the device, dumped and stole Active Directory metadata, and deployed multiple custom and malicious tools capable of facilitating follow-on attacks, credential testing and hunting for administrator passwords, recovery keys and other passwords.

“Based on Volexity’s observations, UTA0576 primarily focused on credential theft, data exfiltration, log tampering, and network reconnaissance,” the company added.

Ivanti encouraged potentially vulnerable customers to act immediately by upgrading to the latest version of software, running the company’s Integrity Checker Tool regularly, and reviewing indicators of compromise published by Volexity.

CISA also urged Ivanti customers to patch the vulnerability quickly, as it dissuaded customers from relying on the company’s Integrity Checker Tool.

“Organizations seeking to determine whether they were compromised will need to conduct network and memory forensics to identify evidence of exploitation,” the agency said in an alert Tuesday. “Ivanti’s Integrity Checker Tool may not detect evidence of exploitation of CVE-2026-104935 because threat actor commands execute in memory.”

Ivanti products, including Ivanti Connect Secure, are a frequent target for attackers of various motivations in the network edge space. 

CISA has flagged 36 Ivanti defects on its known exploited vulnerabilities catalog since late 2021. At least 6 defects across Ivanti products have been exploited since late January.

“Edge devices are a valuable initial foothold and often enable attackers to pivot further into targeted networks,” Koessel said. “It would be fair to expect widespread exploitation, this is a common theme with most vulnerabilities in edge devices.”

Other researchers also expect exploitation to pick up rapidly. 

“Given the history of attacker attention and focus Ivanti Connect Secure has previously drawn — and the trivial nature of the authentication bypass — widespread, indiscriminate exploitation is inevitable as attackers begin reviewing patches and public information,” said Yordan Ganchev, principal threat intelligence specialist at watchTowr.

“The race condition required for code execution offers little resistance, as an unauthenticated attacker can repeatedly attempt exploitation until it succeeds,” he added.

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Citrix customers just got through back-to-back weekends filled with varying levels of uncertainty and worry, as yet another actively exploited zero-day vulnerability was discovered in Citrix NetScaler products.

Researchers and security experts said the vulnerability — CVE-2026-88779 — is less concerning because exploitation triggers denial of service and only impacts instances that have SAML (security assertion markup language) enabled. 

“This means it doesn’t work out of the box against every NetScaler deployment,” Jake Knott, head of threat intelligence at watchTowr, told CyberScoop. “While this is very inconvenient, it doesn’t have organizations scrambling to trigger incident response.”

Citrix was much quicker and consistent in alerting customers to the emerging threat Friday, and followed up the next day with a more detailed blog post and security advisory that contained a patch for the high-severity defect. 

“After we were alerted to this issue we immediately developed and published a mitigation while concurrently developing, testing and deploying a fix,” a company spokesperson said in a statement. “The fix for this issue is available, and we urge all customers to quickly apply it to their NetScaler instance.”

The Cybersecurity and Infrastructure Security Agency added the defect to its known exploited vulnerabilities catalog Sunday.

The vendor’s response also provided some relief for customers and researchers who spent much of the previous weekend rushing to assess widespread rumors of other defects in the assailed network edge gateways. In that case, Citrix took most of the weekend to confirm attackers were actively exploiting a pair of NetScaler zero-days, some of which researchers said remained undetected for at least three weeks.

“Citrix did a better job with their response to this vulnerability,” and took steps that enabled customers to make their own risk-based decisions with more currently available information, said Joe Toomey, vice president of underwriting security at insurance provider Coalition. 

“Although it’s difficult to celebrate given this is the third publicly-exploited NetScaler zero-day vulnerability in a two-week window, it is a step in the right direction,” he added. 

Citrix declined to say how many customers are impacted by the latest zero-day or when the first instance of exploitation occurred. Yet, Knott at watchTowr said exploitation likely began Friday. 

The newer defect doesn’t share any technical links with the pair of zero-days Citrix disclosed less than a week prior, but it can accelerate one of those vulnerabilities — CVE-2026-88771 — by intentionally crashing machines to speed up exploitation, Knott said.

While risk is currently perceived low for CVE-2026-88779, it is “incredibly simple to trigger, with a single specially crafted request being all that is needed to knock an appliance offline,” Knott added. “Exploitation is already occurring in the wild, and disrupting an authentication gateway can prevent legitimate users from accessing the services behind it.”

Toomey also described the denial-of-service vulnerability as less serious than the previous week’s actively exploited zero-days. Yet, he noted, exploitation attempts of CVE-2026-88779 “clearly contain shellcode that implies that the threat actor believes they can use this vulnerability, or chain it with another vulnerability, in order to achieve remote-code execution.”

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Attackers remained undetected for more than three weeks as they exploited a critical zero-day vulnerability affecting Citrix NetScaler appliances en masse. 

The earliest known instance of CVE-2026-88772 exploitation occurred Sept. 3, Mandiant researchers told CyberScoop Tuesday. 

The besieged security vendor and researchers didn’t confirm the attacks until late last week. By then, Mandiant says, organizations in North America and Europe spanning the government, financial services, education, telecom, legal and professional services sectors were already likely compromised.

“We are aware of dozens of impacted organizations,” Charles Carmakal, chief technology officer at Mandiant Consulting, wrote in a LinkedIn post. He attributed the attacks to “advanced and suspected state-sponsored threat actors.”

The three-week gap — at minimum — between initial exploitation and confirmed in-the-wild attacks gave attackers a significant advantage. 

Mandiant warned that the gap could be even wider. “We are still responding to active intrusions, and new evidence may change our understanding of the campaign timeline,” researchers who published a threat intelligence report on the attacks Tuesday told CyberScoop in an email. 

The incident response firm’s analysis on the latest zero-day attack spree targeting Citrix customers underscores the multi-layered mess network defenders have been responding to since Saturday.

The zero-day exploits in Mandiant’s report only cover half of the problem. Attackers have also exploited a second Citrix NetScaler zero-day — CVE-2026-88771 — since at least Sept. 24, according to GreyNoise, but researchers said that campaign likely started earlier as well.

It’s unclear to what extent the pair of zero-days are linked. But, nearly two days after the first unconfirmed rumors of the attacks surfaced, Citrix disclosed both of the actively exploited defects in a security advisory Sunday, releasing patches for them and six additional vulnerabilities.

Mandiant researchers uncovered multiple novel tools and tactics attackers used to exploit CVE-2026-88772, gain privileged access to compromised environments, hop around the network and steal sensitive data. A threat actor in one observed intrusion routed traffic through novel tunneler malware to “manually conduct internal reconnaissance and credential theft,” researchers wrote. 

Researchers at watchTowr also published technical analysis of CVE-2026-88782 Tuesday.

The attacks from multiple fronts, involving two zero-days, reflect an alarming and sustained pattern of malicious activity targeting so-called edge devices, such as virtual private network gateways and firewalls. 

Vulnerabilities in these devices accounted for 48% of the enterprise-related zero-days last year, according to Google Threat Intelligence Group.

“Our previous research corroborates that both cyber espionage and financially motivated threat actors prioritize exploiting vulnerabilities in edge devices and security appliances,” Mandiant researchers wrote in response to questions on their report. 

“Because most edge devices do not support endpoint detection and response (EDR) monitoring, targeting them, particularly through exploiting zero-day vulnerabilities, provides threat actors with an infection vector that is difficult to detect and prevent, and the opportunity to scale a campaign as long as the exploit remains undiscovered,” the researchers added. 

Carmakal, in his LinkedIn post, warned that Mandiant expects “broad and opportunistic exploitation” of both of the Citrix NetScaler zero-days by a variety of threat actors in the near term.

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Citrix took most of the weekend to confirm that attackers were actively exploiting the newest round of NetScaler zero-days, leaving network defenders and threat hunters to react without official confirmation. 

Yet, behind the scenes, multiple CERTs, advisory firms, insurance providers, researchers and chatty security professionals warned their respective peers and communities of a live and serious threat. 

Nearly two days after the first unconfirmed rumors, Citrix published a security advisory Sunday disclosing the exploited zero-days, CVE-2026-88771 and CVE-2026-88772, releasing patches for them and six additional defects.

By then, criticism was at a fever pitch, and for some NetScaler customers the warning came too late. 

“The information vacuum was most striking. Customers were receiving warnings through unofficial channels while Citrix remained publicly silent,” Ben Harris, founder and CEO at watchTowr, told CyberScoop. 

“Customers were left without communication, guidance, or even acknowledgement that the vulnerability that was rumored to exist was real. Citrix could have warned customers that active exploitation was occurring and provided immediate defensive guidance without disclosing technical details that would help attackers,” he added. 

“When active exploitation is underway, hours matter,” Harris said.

Citrix did not directly answer questions about the lengthy communication delay. 

“We recently identified critical vulnerabilities in Citrix NetScaler ADC and Citrix NetScaler Gateway that led us to immediately develop and release a new version of the software that addresses the issues,” the company said in a prepared statement.

The critical defects are both rated 9.5 on the CVSS scale and allow attackers to achieve remote code execution. 

Researchers are particularly concerned about CVE-2026-88771, a command-injection vulnerability that affects all NetScaler appliances in a default configuration. That gives attackers a broad pool of targets and a better chance at successful exploitation. A proof-of-concept exploit for the vulnerability is also publicly available. 

Palo Alto Networks said it identified more than 50,000 publicly exposed instances of Citrix NetScaler devices potentially vulnerable to both of the zero-days as of Sunday. 

The earliest known exploitation attempt occurred Sept. 24 when GreyNoise said it observed an unsuccessful exploitation attempt against a Citrix NetScaler Gateway under its control for malicious activity scanning purposes. But researchers warn that exploitation likely started before then.

Citrix did not say how many customers have been compromised thus far and researchers are still assessing the fallout.

Citrix said it is making generic indicators of compromise available to customers in their user consoles, and the company referred to previously issued guidance for customers who suspect compromise. 

Attribution for the attacks is also still under investigation, yet NetScaler products are a common, recurring target for financially-motivated cybercriminals and state-sponsored espionage groups. 

The Cybersecurity and Infrastructure Security Agency issued an alert Sunday after Citrix publicly confirmed the attacks on its customers, and added CVE-2026-88771 and CVE-2026-88772 to its known exploited vulnerabilities catalog. The vendor has appeared on the agency’s list of vulnerabilities known to be exploited five times this year, and a total of 26 times since late 2021.

Security leaders across the industry — including Charles Carmakal, chief technology officer at Mandiant Consulting, and Wendi Whitmore, chief security intelligence officer at Palo Alto Networks — also sprung into action Sunday, with direct warnings on LinkedIn about the urgent threat. 

The information vacuum that persisted through most of the weekend put cybersecurity professionals in sometimes unique positions. Joe Toomey, vice president of underwriting security at insurance provider Coalition, said the company notified potentially vulnerable customers with limited official data and no confirmation from CISA or Citrix.

In a LinkedIn post Sunday, he called Citrix “unconscionably irresponsible” for remaining silent for more than 36 hours after word began circulating about in-the-wild exploitation.

“I fully understand a vendor embargoing specific details about a vulnerability when a patch has not yet been published, but once the vuln is exploited in the wild, some of those rules no longer apply,” Toomey wrote.

Citrix and its customers are in familiar territory. The vendor’s products have been widely targeted in previous attack sprees, often involving zero-day exploits and some infamously referred to as CitrixBleed and CitrixBleed 2.

“Citrix has a history of delaying the publication of vulnerabilities, even when they’re being exploited in the wild and affecting customers. Citrix eventually released patches and an advisory, but an adequate response also requires timely, clear communication,” Harris said. 

“Customers shouldn’t have to rely on unofficial warnings, security researchers, and third parties to learn that critical infrastructure may already be compromised,” he added. “This latest incident raises serious questions about whether Citrix has learned from previous crises and meaningfully improved how it protects and informs customers.”

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Volexity researchers spotted another state-aligned Chinese threat group exploiting a triple-link chain of zero-day vulnerabilities across multiple campaigns, the company said in a blog post Monday.

The threat group it tracks as UTA0565 exploited the vulnerabilities in Chrome and Microsoft between Sept. 3 and 4 before the defects were disclosed or patched, researchers said.

The timing of the malicious activity mirrors other spikes threat hunters observed and attributed to multiple Chinese espionage threat groups. Yet, Volexity noted UTA0565’s campaigns differed from those attacks by using multiple fake websites to deceive victims.

Volexity shared phishing emails UTA0565 sent to Asian government entities urging them to publicly support imprisoned Hong Kong activist Chow Hang-tung. The group spoofed domains impersonating the Center for American Progress and China Digital Times in other phishing emails.

While UTA0565 showcased a variance in tactics, it used the same components researchers observed in previous instances of the exploit kit across multiple Chinese threat groups.

“This seemingly widespread adoption across multiple threat actors suggests a coordinated effort within the Chinese computer network exploitation community, where the core kit was likely shared, customized, and weaponized by multiple groups,” Volexity wrote in the blog post. “The activity reported so far reflects only two organizations’ observations; the full scope and impact are likely far broader.”

The vulnerabilities include: CVE-2026-85046 and CVE-2026-87491, remote-code execution defects in the JavaScript engine for Chromium-based browsers; and CVE-2026-85880, a privilege-escalation zero-day that Microsoft disclosed Sept. 8 in Windows Advanced Local Procedure Call. 

Proofpoint, which previously observed multiple state-aligned threat groups chaining the vulnerabilities together in attacks since last August, said a limited group of organizations were exposed to all three vulnerabilities in a short window. 

Proofpoint previously attributed attacks involving the zero-days to APT31, UNK_LateNight, UNK_DoubleCheck and UNK_QuietRacket. At the time it warned that attackers of other origins and motivations could strike soon as well.

Volexity said UTA0565 used a payload from a previously undocumented malware family it tracks as “CLEANGULP.” Researchers also found several domains likely used by UTA0565 in similar campaigns targeting media organizations, halal restaurant search websites and corporate training organizations. 

“UTA0565’s use of the zero-day vulnerabilities shows technical and operational improvements over other campaigns observed by Volexity, both in the mechanics of the exploitation and the presentation to end users,” researchers wrote. “Using real content from legitimate websites as decoy material continues to be an effective way to reduce user suspicion.”

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Cisco disclosed its second actively exploited zero-day vulnerability in as many days, presenting its customers with back-to-back threats to address in unrelated products.

The latest zero-day — CVE-2026-76460 — has a maximum-severity rating and was exploited before Cisco disclosed and patched the vulnerability Wednesday. The defect in an API of Cisco Identity Services Engine (ISE) allows a remote attacker to bypass authentication and gain full control of the affected device.

“ISE devices enforce network access policy, so root access on the appliance lets an attacker modify that policy, extract stored credentials, delete logs, and move laterally into every network segment ISE controls,” Landon Rice, senior exploit developer at VulnCheck, told CyberScoop.

Cisco did not say how many organizations have been compromised thus far, but reported it found the vulnerability during a technical support case. 

“Cisco is aware of active exploitation of this vulnerability. We strongly recommend customers upgrade to available fixed software and follow guidance in the advisory,” a Cisco spokesperson said in a statement.

The Cybersecurity and Infrastructure Security Agency added the zero-day to its known exploited vulnerabilities catalog shortly after Cisco’s disclosure. 

Researchers haven’t attributed attacks involving CVE-2026-76460 to any known group or threat actor, but Rice noted Cisco ISE vulnerabilities are a recurring target. 

Multiple vulnerabilities affecting the Cisco product have been exploited since June 2025, including CVE-2025-20337 and CVE-2025-20281. The latest zero-day vulnerability and the pair of defects disclosed in the summer of 2025 were all rated critical with the highest rating of 10. 

Cisco didn’t say when the first instance of CVE-2026-76460 exploitation occurred, but the disclosure came just two days after the vendor disclosed CVE-2026-76461, an actively exploited zero-day vulnerability in Cisco Secure Email Gateway. 

While the two zero-days disclosed this week have consecutive CVE identifiers, there’s no indication they are connected or share any technical relationship, Rice said. “These are different products and different vulnerability classes with no relation,” he added.

A Cisco spokesperson concurred with that assessment. “CVEs are assigned on a first-come, first-served basis, so consecutive numbering reflects assignment order rather than any relationship between the issues. CVE-2026-76460 and CVE-2026-76461 affect different codebases,” the spokesperson added.

Cisco published indicators of compromise to help customers hunt for attempted exploitation in their environments, and said there are no workarounds for the vulnerability.

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Attackers of unknown origins and motivations are exploiting a critical zero-day vulnerability in Cisco Secure Email Gateway, authorities and researchers said Monday.

The vulnerability — CVE-2026-76461 —  was exploited before Cisco disclosed and patched the defect Monday and allows unauthenticated, remote attackers to execute commands with root privileges on vulnerable systems. “In practical terms, that gives the attacker control of the gateway itself,” Douglas McKee, director of vulnerability intelligence at Rapid7, told CyberScoop.

Cisco said its product security incident response team became aware of active exploitation of the defect affecting Cisco AsyncOS Software for Cisco Secure Email Gateway in September. When asked for further details, a company spokesperson pointed to the advisory and reiterated that the company is aware of active exploitation of the vulnerability.

The company did not say how many organizations are impacted by active exploitation thus far, but it indicated multiple customers were likely compromised prior to disclosure. 

“Cisco has conducted a thorough threat intelligence investigation on devices that belong to Cisco Secure Email Cloud. Cisco has directly contacted customers who own Cisco Secure Email Cloud devices where indicators of possible compromise were identified,” the company wrote in its security advisory. “Cisco is engaged in remediation and recovery operations. Cisco has already deployed mitigations that are within Cisco’s management.”

The Cybersecurity and Infrastructure Security Agency added the zero-day, which affects cloud-based and on-premises instances of Cisco Secure Email Gateway, to its known exploited vulnerabilities catalog shortly after Cisco’s disclosure. 

The tight timeline between Cisco’s public advisory and patch guidance, and CISA’s quick addition to the KEV catalog indicates the vulnerability deserves immediate attention, McKee said. 

“The combination here is pretty ugly. No authentication is required, an attacker can reach the vulnerable code by sending an email through the appliance, successful exploitation can result in root-level command execution, and Cisco has observed exploitation in the wild,” he added.

Researchers at Rapid7 and VulnCheck said they don’t yet know how many organizations are impacted by active exploits, but they encouraged Cisco customers to patch and hunt for potential signs of compromise as soon as possible. 

Spencer McIntyre, director of exploit development at VulnCheck, told CyberScoop the exploit could allow an attacker to maintain access to the email gateway and monitor communications. “Stealing or silently snooping on email comms is a common tactic for state-sponsored and other threat actors conducting espionage operations,” he said. 

“It’s going to be worse for organizations that have the appliance deployed on-premises. In this case, the attacker could pivot internally,” McIntyre added. “If, however, organizations use a cloud instance, the compromised gateway is less likely to have significant access to internal organizational resources.”

Cisco released indicators of compromise to help customers hunt for attempted exploitation in their environments, but the company added that attackers could remove or hide those traces with the level of access granted via exploitation.

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Microsoft addressed 974 defects across its product suite, including two actively exploited zero-day vulnerabilities, in its monthly Patch Tuesday security program. 

The massive batch of patches, Microsoft’s largest ever, reflects a continuing trend for the vendor as it leans on artificial intelligence to discover more vulnerabilities at a faster rate. Yet, the recent period of record breaking vulnerability disclosures hasn’t resulted in a flood of actively exploited zero-days.

“AI-assisted vulnerability discovery shows no signs of slowing down,” Dustin Childs, head of threat awareness at Trend Micro’s Zero Day Initiative, wrote in a blog post Tuesday. “However, we have not seen a correlating spike in active exploits — yet.”

The vulnerabilities actively exploited prior to disclosure — CVE-2026-81963 affecting the Windows Update Stack and CVE-2026-85880 affecting Windows Advanced Local Procedure Call — both have CVSS ratings of 7.8 and allow attackers to escalate privileges. 

More than 1 in 10 defects Microsoft disclosed in this month’s security update are rated critical. The update included 723 vulnerabilities in Windows, 111 in Office, 111 in Office 2016, 62 in SQL and 22 spanning various developer tools.

Researchers encouraged security teams and customers to not get overwhelmed by the total number of defects, but instead focus on their specific areas of risk and exposure. 

“While the number of vulnerabilities being patched is rising, the number of vulnerabilities that can and will affect most organizations remains quite low. AI-assisted vulnerability discovery in 2026 is creating larger haystacks, but it isn’t finding more needles,” Satnam Narang, senior staff research engineer at Tenable, said in an email. 

“It’s critical that organizations understand which vulnerabilities actually apply to them, whether they pose a threat by being reachable and exploitable, and prioritize remediation based on this risk context,” he added. 

Jack Bicer, director of vulnerability research at Action1, drew a similar conclusion from the record-breaking Patch Tuesday. 

“At this scale, the challenge is not simply getting through the patch list but knowing what needs attention first,” he said. “With hundreds of updates landing at once, IT and security teams need to quickly separate the vulnerabilities that demand immediate action from those that can follow the normal deployment cycle.”

The full list of vulnerabilities addressed this month is available in Microsoft’s Security Response Center.

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A notorious cybercrime group has once again exploited a critical zero-day vulnerability on a large scale, claiming it stole data from dozens of organizations, including some of the world’s largest publicly traded companies.

Clop, a prolific but calculated data theft extortion group that’s been active since 2020, began sending threatening emails to its alleged victims in mid-July, according to researchers. 

The fallout from the attack spree, which followed a familiar pattern for Clop and its targeted pool of victims, is still evolving as companies hunt for potential signs of compromise.

The vulnerability at the center of Clop’s latest campaign affects a pair of software products from PTC — Windchill and FlexPLM — which manufacturers and retailers, particularly in the manufacturing, aerospace, and automotive industries, use to automate supply chain systems and manage product lifecycles.

“This continues Clop’s trend of targeting SaaS logistics companies’ platforms with zero-days and carrying out mass-exploitation campaigns,” Allan Liska, field chief information security officer at Recorded Future, told CyberScoop.

PTC disclosed the vulnerability — CVE-2026-12569 — on June 17 and issued a patch and initial indicators of compromise the following day. 

Yet, that was too late for some of Clop’s known victims who were likely compromised by exploitation of the zero-day in early June, according to Ransom-ISAC.

The Cybersecurity and Infrastructure Security Agency added the defect, which allows unauthenticated attackers to execute code remotely, to its known exploited vulnerabilities catalog June 25.

PTC consistently added new indicators of compromise as they were discovered by researchers. But the company hasn’t said how it first became aware of the vulnerability and ensuing attacks, when the earliest known instance of exploitation occurred or how many customers are known to be compromised. 

PTC did not respond to a request for comment. 

Clop’s claimed victim set is diverse. The point-of-sale restaurant management platform Toast and software vendor Zebra both told CyberScoop they detected and contained system intrusions, but claimed limited impacts. Other alleged victims, including GE, Philips and Shell, did not respond to requests for comment. 

Researchers continue to uncover new details about the tools Clop used once it exploited and gained access to PTC customer systems. ReliaQuest said the group used a custom web shell that gave attackers a direct path to credential theft and large-scale data theft.

The fully equipped extortion platform, which was purpose-built for Windchill, decrypts credentials, delivers malware, and includes tools for sustained access, network traversal and data encryption, ReliaQuest researchers wrote in a report Tuesday.

The toolkit allows attackers to move quickly from initial access to data theft and additional post-exploitation activity without executing manual commands — a framework that mimics Windchill’s standard functions and limits defenders’ ability to detect any malicious activity.

“This campaign is another reminder that Clop remains a sleeping dragon, always looking and preparing to mass exploit vulnerabilities in software that holds sensitive data,” ReliaQuest researchers wrote in the report. “The group commonly goes inactive between campaigns but springs to life with custom-built web shells whenever there is another opportunity for mass extortion.” 

The drawn-out impact of Clop’s latest attack spree also mirrors some of its previous campaigns. The threat group has successfully exploited zero-days across multiple technology vendors’ systems, allowing it to steal sensitive data for weeks — sometimes months — from many downstream customers.

Clop targeted dozens of Oracle E-Business Suite customers for more than three months, beginning in the summer of 2025, before it started bombarding victims with extortion emails. The group also achieved mass exploitation as it infiltrated MOVEit environments in 2023, ultimately exposing data from more than 2,300 organizations, making it the largest and most significant cyberattack that year.

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Researchers said INC ransomware, one of the most active ransomware groups globally, has been the main attacker exploiting a pair of SonicWall zero-days soon after they were disclosed last month.

The prolific ransomware-as-a-service operation wasn’t the first group to exploit the flaws, which were actively exploited for three weeks before the vendor disclosed and patched the defects July 14, but it has been the most assertive and concerning group to target and chain both vulnerabilities together for full access.

“Since public disclosure, INC ransomware has emerged as the most commonly named threat actor actively weaponizing this vulnerability chain,” Brett Deroche, director of incident response at Rapid7, told CyberScoop. “While Inc is the name driving the post-disclosure wave, we can’t attribute the full body of exploitation to INC specifically.”

SonicWall did not respond to a request for comment.

The SonicWall vulnerabilities — CVE-2026-15409 and CVE-2026-15410 — are the latest in a series of security issues confronting the vendor’s customers, including actively exploited zero-days, previously disclosed defects, and an attack last year that allowed a state-sponsored threat group to steal the firewall configurations of every SonicWall customer. 

Just last week, Huntress researchers spotted an attack spree that compromised 30 SonicWall customers in less than two days. 

Ransomware groups have taken a special interest in SonicWall. Ten of the 17 SonicWall defects added to the Cybersecurity and Infrastructure Security Agency’s known exploited vulnerabilities (KEV) catalog since late 2021 are known to be used in ransomware campaigns.

INC ransomware, which has claimed nearly 900 victims across 71 countries since it was first discovered three years ago, is just the latest financially-motivated group to target SonicWall customers. 

Researchers haven’t determined how many organizations have been impacted by the latest SonicWall zero-days, including attacks linked to INC ransomware. 

“Attribution here isn’t a single clean answer. The earliest exploitation we observed, beginning June 22, traced back to common hosted infrastructure, though those attacks were largely unsuccessful,” Deroche said. 

“INC’s confirmed activity that we’ve observed came after public disclosure, using different infrastructure and moving from initial access to ransomware deployment in short order. That’s a meaningfully different operational tempo and skill level than what we saw pre-disclosure,” he added. 

Deroche said Rapid7 has successfully prevented data theft and encryption in the majority of recent cases, yet noted ransomware was deployed in at least one case the security vendor observed.

Yet, there could be other attacks outside the purview of Rapid7’s telemetry. INC ransomware has listed multiple new alleged victims on its data leak site, including organizations and government agencies in Australia, the United States, the United Arab Emirates, Colombia and Switzerland, Resecurity said in a blog post Saturday.

The company said it has aided several victims with incident response, and learned multiple victims received emails and phone calls from alleged hackers who pressured them to engage in negotiations.

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A Russian state-sponsored threat group has been stealing sensitive data from governments and commercial organizations since July 2025 via a novel exploit in popular Linux-based enterprise software, U.S. authorities and cyber officials from more than a dozen other countries warned in a joint cybersecurity advisory Thursday.

Laundry Bear’s most recent espionage campaign involves the exploitation of a zero-day vulnerability in Zimbra Collaboration Suite that wasn’t patched until November 2025, five months after attacks were well underway, officials said. 

The exploit just requires a view — no clicks — and allows attackers to steal the previous 90 days’ worth of email, the account’s password, search history, the victim organization’s email directory, two-factor authentication tokens and other newly created passwords.

“The covert and persistent nature of this activity, along with the absence of any known financial extortion, almost certainly indicates this group’s involvement in espionage activities with Russian government backing,” officials wrote in the advisory. 

“Additionally, extensive Ukrainian targeting, prior to use against U.S. and other NATO allies, outlines an increasing trend within Russian cyber threat groups to target Ukrainian users first—both as a priority target and as a testbench for malicious cyber techniques before broader global deployment.”

The state-sponsored espionage group, also known as Void Blizzard, has compromised governments and organizations in the defense, education, energy, law enforcement, media, finance, transportation and technology sectors. 

Laundry Bear’s year-long campaign involving the exploitation of CVE-2025-66376 showcases more technical capabilities, including a custom JavaScript payload it delivers to targeted victims via phishing emails. The threat group could also likely adapt the novel data exfiltration and aggregation capability, dubbed “beehive,” to exploit other vulnerabilities, officials warned.

The defect’s medium-severity rating of 6.1 underscores the challenge defenders regularly confront in prioritizing patching schedules based on measure of severity alone.

The Russian state-supported group, which has been active since at least 2024, is still actively exploiting Zimbra Collaboration Suite instances that remain unpatched, officials said.

Authorities shared Thursday indicators of compromise, mitigation steps and urged organizations to update their vulnerable software.

“This campaign’s targeted victimology and limited exploitation capabilities likely indicate this group manually identifies and targets the victim organizations” by identifying organizations with public-facing infrastructure, officials wrote in the advisory.

Once a target is identified, Laundry Bear also likely compiles email addresses for users to target with the exploit via phishing emails. Officials did not identify specific victims or describe the volume of organizations already compromised.

The joint cybersecurity advisory was issued by the United States, Australia, Canada, New Zealand, the United Kingdom, Czech Republic, Denmark, Estonia, Finland, France, Italy, Moldova, the Netherlands, Poland, Spain and Sweden.

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SonicWall customers are attempting to dodge another security challenge as attackers are exploiting a pair of zero-day vulnerabilities that have been confirmed by the vendor. 

The company publicly disclosed the vulnerabilities — CVE-2026-15409 and CVE-2026-15410 — in a security advisory Tuesday. SonicWall credited an employee with discovering the defects, but it hasn’t said when the discovery occurred or the earliest known instance of exploitation. 

Rapid7 researchers told CyberScoop both vulnerabilities were first exploited June 22. “From the cases that our team has observed, the goal is likely ransomware, though we have prevented the actors from achieving exfiltration and encryption,” said Seth Lazarus, senior manager of detection and response services at Rapid7.

Overlapping tactics, techniques and procedures from the attacks observed by Rapid7 indicate the same threat group or attacker discovered and exploited the zero-days, Lazarus added.

SonicWall did not answer questions about the impacts of these attacks thus far, and the company hasn’t attributed the attacks to a known group or described the attacker’s origins and motivations.

The vendor did, however, confirm to CyberScoop that both vulnerabilities have been chained together for exploitation. The vulnerabilities affecting SonicWall SMA1000 appliances, including a max-severity defect that allows attackers to make authenticated requests and a 7.2-rated vulnerability that allows authenticated command injection.

“When these two are chained, an attacker can go from zero access to a complete system compromise for the affected appliance,” said Landon Rice, senior exploit developer at VulnCheck.

Ben Harris, founder and CEO at watchTowr, said two characteristics of the vulnerabilities fuel a sense of dread. “Both were exploited as zero-days before fixes were available, and together they offer a plausible path to remote-code execution from the internet,” he said.

The Cybersecurity and Infrastructure Security Agency added both zero-days to its known exploited vulnerabilities catalog Tuesday. 

SonicWall encouraged customers to patch the vulnerabilities by upgrading to the latest software version, which it released upon disclosure, and shared some indicators of compromise to help customers hunt for potential malicious activity on their systems.

“Speed of response was a priority for us,” said Bret Fitzgerald, senior director of global communications at SonicWall. “Within days of becoming aware of the issue, our team had developed a script that we can run on behalf of affected customers to assist with resolution, and mitigation efforts are already underway.”

SonicWall and third-party researchers haven’t said how many SonicWall customers are impacted by the exploited vulnerabilities, but the vendor did say it already investigated multiple cases of active exploitation. 

Fitzgerald said the company monitors about one million sensors globally and “SMA1000 appliances represent a very small subset of that footprint, less than 5,000 units.”

SonicWall said support staff are also helping customers work through instances of suspicious activity, warning that patching alone is not sufficient. 

The vendor and its customers have been hit by a barrage of actively exploited zero-days and previously disclosed defects in SonicWall devices for years. In 2025, an undisclosed state-sponsored threat actor intruded the company’s cloud environment and stole firewall configurations of every SonicWall customer. 

Seventeen defects affecting the vendor’s products have been added to CISA’s known exploited vulnerabilities catalog since late 2021. Ten of those defects are known to be used in ransomware campaigns, according to CISA, including a wave of about 40 Akira ransomware attacks between mid-July and early August.

“As always,” Harris said, “when something is confirmed as already exploited in the wild, patching is the bare minimum, and breach should be assumed.”

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