Security teams have never lacked vulnerability data. The harder problem is deciding which issues create a credible path to business impact, then acting before that path can be used. As frontier AI makes it faster and less expensive to connect weaknesses, operational assumptions, and legitimate system behavior, that decision window is becoming even tighter.

The Gartner® report, Mythos Reprioritizes Cybersecurity Outcomes and Investments, examines what this shift means for cybersecurity priorities and investment. Rapid7 is offering complimentary access to the research, which we believe can help security leaders reassess how they prioritize exposure and infrastructure teams reassess how they plan response and recovery.

Why does AI change the vulnerability management equation?

Gartner states, “Mythos collapses the distance between theoretical weaknesses and executable attack scenarios, forcing cybersecurity to optimize for outcomes, not activity.” For leaders already managing more vulnerabilities than their teams can address, the pressure comes from the growing speed at which separate weaknesses can become a credible attack path.

The change also extends beyond one model. Gartner states, “By 2027, Mythos will be overtaken by new frontier-AI-enabled models, signaling that this moment is not about Mythos, but a new era of AI-assisted vulnerabilities and functional exploits.”

At Rapid7, we believe this requires a more attacker-aware view of exposure. A large backlog can contain thousands of issues with very different implications for the organization. Leaders need to understand which exposures are reachable, how they could be combined, which business services they affect, and what action would reduce risk most effectively.

What should security leaders measure instead?

Vulnerability counts, backlog size, and generic remediation targets show how much work a team has completed. They provide less clarity on whether an attacker’s options have narrowed or whether the organization can respond and recover more effectively.

Gartner advises, “Organizations must shift focus from volume and activity to speed of decision, effectiveness of response, and tangible reduction of enterprise risk in an environment where attacker reasoning scales rapidly.”

The report examines outcome-driven measures including “Attack path analysis coverage,” “Patching cadence,” “Compensating control deployment cadence,” “Mean time to remediate,” and “Technology debt.” We believe this gives leaders a stronger basis for connecting security investment with reduced exposure, faster action, and business resilience.

How can teams move from prioritization to action?

Better prioritization only creates value when teams can act on it. Gartner recommends, “Use attack path analysis to prioritize your patches, virtual patches, and compensating controls. This can scale down to a consideration of critical services mapped into critical business outcomes and exposure.”

Rapid7’s internal, practitioner-led exploration of Claude Mythos Preview through Project Glasswing reinforces our view that faster discovery is only the beginning. A model may help identify and validate a potential vulnerability, but reducing exposure still requires teams to understand affected systems, apply business context, choose the right remediation or compensating control, verify the result, and maintain detection coverage.

Rapid7’s vulnerability management capabilities support this operational path by bringing attack-surface visibility, threat intelligence, business context, and attack-path analysis together, helping teams identify which exposures matter most and coordinate remediation through existing workflows.

What does an outcome-led program look like?

An outcome-led program gives executives a clearer answer to a more useful question: which attacker opportunities did we reduce, and how quickly could we respond? It also supports ongoing decisions about technical debt, recovery planning, and where limited resources can deliver the greatest reduction in business risk.

Access the complimentary Gartner report, Mythos Reprioritizes Cybersecurity Outcomes and Investments, to explore how AI-assisted vulnerability discovery may change cybersecurity priorities, metrics, and investment decisions.

⠀

Gartner, Mythos Reprioritizes Cybersecurity Outcomes and Investments, Paul Proctor, John Watts, Emily Tan, 28 May 2026.

GARTNER is a trademark of Gartner, Inc. and/or its affiliates in the U.S. and internationally and is used herein with permission. All rights reserved.

Gartner does not endorse any vendor, product, or service depicted in its research publications and does not advise technology users to select only those vendors with the highest ratings or other designation. Gartner research publications consist of the opinions of Gartner’s research organization and should not be construed as statements of fact. Gartner disclaims all warranties, expressed or implied, with respect to this research, including any warranties of merchantability or fitness for a particular purpose.

Kalleigh Lane reports: If your school district used Frontline Central or School Health Management, your Social Security number, date of birth, or government ID could have been caught up in a cybersecurity incident. That risk applies to some adults and minors whose information was processed through those products. Frontline Education announced Oct. 26, 2026, that...

Risk managers are trained to spot weak signals, plan for disruption and make hard decisions under uncertainty. But the discipline looks different when the risk is not a system or an enterprise, but you.

The post When Risk Becomes Personal: What Security Leaders Can Learn From a Cancer Diagnosis appeared first on SecurityWeek.

The process that gates nearly every B2B deal is a self-assessment the sender distrusts and the receiver accepts. There is finally a better basis for trust between companies.

The post Nobody Trusts the Security Questionnaire. We Rely on It Anyway. appeared first on SecurityWeek.

Security teams cannot keep responding faster forever. As AI helps attackers accelerate reconnaissance and exploitation, organizations need to reduce the opportunities that make attacks possible in the first place.

Bitdefender rolled out new functionality in Bitdefender GravityZone, a unified cybersecurity platform that provides prevention, protection, detection, and response capabilities for organizations of all sizes. These features, aligned with our multi-layered security strategy, are designed to reduce the workload for security analysts, administrators, and users.

Protections have been added against scams and social engineering, including new site warnings and server-side Gemini analysis.

The post Google Hardens Chrome Against ClickFix Attacks, Insecure HTTP Connections appeared first on SecurityWeek.

The private keys associated with eight certificates were compromised, and root programs and trust stores are blocking them.

The post Browsers Block eMudhra Intermediate CAs Over Recoverable Private Keys appeared first on SecurityWeek.

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.

The post Microsoft drops an actively exploited zero-day among record high of 1,413 vulnerabilities appeared first on CyberScoop.

Microsoft is publishing 1,413 own-product vulnerabilities on October 2026 Patch Tuesday, including 1,102 vulnerabilities in Windows. Anyone who enjoyed last month’s record-setting Patch Tuesday will love the October 2026 edition, because it’s much bigger still. As Rapid7 has noted over the course of 2026, there is every reason to suppose that vulnerability volumes will continue to rise. Microsoft is aware of exploitation in the wild for just one of the vulnerabilities published today, as well as public disclosure for two others.

Windows Shell: zero-day security feature bypass

The Windows Shell is Microsoft’s term for the GUI interaction logic for the entire OS provided by explorer.exe and associated libraries and APIs, and for the second time this year, the Windows Shell is the site of an exploited-in-the-wild zero-day vulnerability. Today’s specimen is CVE-2026-96951. Once again, the immediate prize for an attacker is a Mark of the Web (MOTW) bypass. What this means is that Windows won’t provide the user with a dialog explaining that Windows protected their PC, because in this case, it didn’t. Exploitation requires that a user opens a specially crafted malicious file or visits an attacker-controlled site, so the evergreen advice about being careful what you click remains valid. Fans of vintage operating systems should note that Windows Server 2012 doesn’t receive a patch, although Server 2012 R2 does. The advisory acknowledges reporters from multiple organizations, although none from within Microsoft. The vulnerability also affected Microsoft’s Outlook.com cloud services, although Outlook.com was patched in a build dated several weeks ago.

.NET Framework: zero-day security feature bypass

Microsoft is aware of some level of public disclosure of CVE-2026-108398, a .NET Framework security feature bypass. Exploitation requires an attacker with an existing foothold to register a malicious .NET assembly for loading by a protected process, bypassing Windows Defender Application Control (WDAC) enforcement. Microsoft rebranded WDAC as App Control for Business several years ago, so you may know it under its new name. The Microsoft Learn page for Application Control for Windows points out that “your organization's data is one of its most valuable assets... and threat actors want it”, and this is, of course, correct. The patch presumably removes an attacker-controlled location from the list of places .NET Framework searches for registered assemblies, which are typically contained within DLLs and executables. If any further indications were needed that vulnerability volumes are increasing industry-wide, this is only the second month that Microsoft has published vulnerabilities with six-digit CVE numbers, but these extra-large CVEs will seem unremarkable from now on.

Outlook: multiple no-interaction RCEs

The sheer volume of vulnerabilities in recent Patch Tuesday releases can easily include several examples of potentially concerning vulnerabilities, each of which might have been more remarkable in its own right back when volumes were lower. Today, Microsoft has published five separate remote code execution vulnerabilities in Outlook where the preview pane is a vector, meaning that simply scrolling past an email in the Outlook reading pane would be sufficient to trigger exploitation. Worse still, Outlook might helpfully display the preview without any user interaction at all. All five of CVE-2026-70242, CVE-2026-97749, CVE-2026-97016, CVE-2026-88156, and CVE-2026-70291 receive fixes in the same patches. No-interaction Outlook preview pane vulnerabilities can sometimes feature prominently in state-backed actor campaigns, with CVE-2023-23397 as a prominent example in this category.

Edge: security updates unclear

In September 2026, Microsoft did not appear to publish any desktop browser security advisories between the start of the month and Patch Tuesday. In October, a slightly different approach has emerged: several recent entries in the Edge security updates release notes mention new versions of Edge which incorporate the latest updates from the Chromium project, but without detailing which vulnerabilities have been fixed, stating instead, “CVE's will be added as soon as available,” and directing readers to the Security Update Guide (SUG). At the time of writing, the SUG lists a total of zero vulnerabilities addressed in Edge in the first 13 days of October, and the “CVE’s added soon” message has been up for over a week. As a result, defenders have no obvious way of knowing which recent vulnerabilities Microsoft has addressed in Edge.

Microsoft lifecycle update

In Microsoft product lifecycle news, today sees Windows 11 24H2 Home & Pro reach end of servicing, while Windows Server 2022 moves to extended support, with free critical security updates continuing but no further feature development. Also this month, the final curtain falls for Windows Server 2012 and 2012 R2 with the expiry of the third and final year of cash-for-updates Extended Security Update (ESU) program for these aging workhorses. Microsoft lists the end of ESU Year 3 on October 14, 2026, in both cases. Microsoft has a long history of providing at least some security patches for products beyond the end of support, with Server 2008 being a case in point, but the time to move past Server 2012 is now. Office 2021 also moves into retirement on October 14; this includes the Long-Term Servicing Channel, with no ESU available in that case.

Also on October 15, 2026, Exchange Server 2016 and Exchange Server 2019 finally join the “no ESU” club, after two previous six-month reprieves. Microsoft seems to really mean it this time, since any future Exchange Server CVEs released by MSRC will stop mentioning Exchange 2016 and 2019. However, Microsoft points out that a lack of warnings does not mean those unsupported versions are not vulnerable to future security issues.

Summary charts

Flock, the controversial public safety company entangled in controversy amid recurring law enforcement abuse of its products, gained authority to assign CVE IDs to vulnerabilities in its own products and grade those defects as a CVE Numbering Authority.

The manufacturer of various surveillance systems, including automated license plate readers (ALPRs) and AI-powered cameras, said it joined the global footprint of more than 550 CNAs to assess, coordinate and prioritize response to vulnerabilities internally.

“It allows us to move faster when researchers report findings, eliminate confusion from duplicate or conflicting vulnerability entries and give our customers a single, trusted source for security information about our products,” Chris Castaldo, chief information security officer at Flock, said in a statement. 

Security experts acknowledge that many vendors are granted CNA authority for good reason. Separately, Flock’s business has drawn considerable public and legal scrutiny over privacy concerns, along with multiple reports of police abusing the technology.

Controversies stemming from such misuse have impacted Flock’s credibility and could cloud how security researchers view the company as a CNA. The development also highlights the limitations of the CVE program, including what constitutes a vulnerability. 

“The measure of Flock as a CNA is whether its records give cities, police departments, and the public enough detail and accuracy to let people track specific risks by product version, the nature of the vulnerability, and ideally how to mitigate or fix it,” Katie Moussouris, founder at CEO at Luta Security, told CyberScoop.

Flock declined to answer questions or make an executive available for an interview, and instead referred back to a blog post.

The company published its vulnerability disclosure policy in August and recently created a security advisories page where it will publish all newly discovered and confirmed vulnerabilities going forward.

Zach Edwards, a security and privacy researcher, noted that numerous activists have done technical teardowns of Flock’s products and said he expects some researchers to continue disclosing Flock vulnerabilities without coordinating with the company.

Researchers last year reported multiple defects in Flock’s license-plate reader and gunshot detection system, which the company submitted for inclusion in the National Vulnerability Database, but deemed not material because the vulnerabilities require physical access to the device. 

“These cameras sit on poles on public streets,” Moussouris said.

Because CNAs are “essentially grading their own homework,” as Edwards put it, credibility and trust have to be earned consistently by properly addressing every defect that meets a reasonable threshold.

“Vendors make sense as CNAs for their own products if they can be trusted to maintain accurate records. They know the code, they can confirm the flaw, and they can tie the record to affected versions and the fix,” Moussouris said. 

“The conflict of interest manifests when they lack the organizational and technical maturity to correctly assess the flaws and their impact,” she added. “A vendor in the CNA role writes the description and often sets the severity score, so an immature vendor may inaccurately represent an issue, either through ignorance or in a misdirected effort to downplay it.”

Flock’s vulnerability disclosure policy specifically disallows testing against live customer deployments, accessing law enforcement or investigative data, physical attacks, denial-of-service testing or social engineering. The company does not run a paid bug bounty program.

“Flock stands out as a CNA because its products track drivers’ movements, its customers are police, and its policy reserves the right to hold back publication if it decides disclosure would create a safety risk to law enforcement or the public,” Moussouris said. “The latter may lead to an abuse in their authority and control of CVEs unless they embrace a more mature customer-safety-first stance of timely, transparent, and accurate vulnerability disclosure.”

Edwards is also dubious about Flock’s position as a CNA, but adds that many vendors, including some offering similar products, are already in the program. 

There are also relatively few norms in how CNAs operate because the responsibility ultimately comes down to each participating vendor. Some companies granted CNA authority are incredibly active while others haven’t publicly disclosed vulnerabilities in their products for years.

“Only time will tell how Flock operates their CVE program and if they issue CVEs for vulnerabilities publicly disclosed,” Edwards said. “But, if their recent history is any indication, they will probably screw it up in some epic way that somehow unites people across the United States to demand CVE issuing reform.”

The post Flock can now issue CVEs for its own products. Should we trust it? appeared first on CyberScoop.

SEC Consult has published technical details on vulnerabilities mentioned in a complaint filed by several US states.

The post TP-Link Faces State Lawsuits and New Scrutiny Over ISP Router Flaws appeared first on SecurityWeek.

Overview

On October 5, 2026, Atlassian published a security advisory for CVE-2026-21589, a critical arbitrary file access vulnerability affecting eight products: Bitbucket Data Center, Confluence Data Center, Jira Service Management Data Center, Jira Software Data Center, Bamboo Data Center, Crowd Data Center, Crucible, and Fisheye. Atlassian assigned the vulnerability a CVSSv4 score of 9.3. An unauthenticated remote attacker who knows a target file's exact name and path can access it within the application's web root; the vulnerability does not provide directory listing or enumeration.

Atlassian's advisory treats all versions before the applicable fixed releases as affected, including unsupported versions. Affected Atlassian Cloud products have already been patched, and no action is required from Cloud customers.

Detailed technical analysis and file-read proof-of-concept scripts are public, so Rapid7 recommends patching on an emergency basis, outside of normal patch cycles, and reviewing access logs for attempted exploitation.

Technical overview

NVD lists files or directories accessible to external parties (CWE-552) as the weakness associated with CVE-2026-21589.

On October 6, watchTowr Labs published a technical analysis based on comparisons of vulnerable and patched Jira, Confluence, and Bitbucket packages. Their analysis identified a path traversal vulnerability in Atlassian's web-resource handling: double-colon (::) sequences can become path separators during request processing, allowing traversal components to reach the resource-loading code, resulting in the contents of arbitrary file being read back to an attacker.

Their testing could not traverse outside the Tomcat context, but could read files throughout the application web root. In an Atlassian Crowd deployment that had Jira configured, reading WEB-INF/classes/crowd.properties exposed application credentials. With network access to Crowd, they used those credentials to create a user and add it to jira-administrators; Crowd's IP allowlisting can block this direct route.

Mitigation guidance

Organizations should upgrade each affected installation to a listed fixed version or the latest available version. Atlassian's October 5 advisory lists the following fixed versions:

Product	Fixed versions
Bitbucket Data Center	9.4.26, 10.2.8, 10.5.1
Confluence Data Center	9.2.26, 10.2.19
Jira Service Management Data Center	5.12.40, 10.3.26, 11.3.12
Jira Software Data Center	9.12.40, 10.3.26, 11.3.12
Bamboo Data Center	10.2.24, 12.1.12
Crowd Data Center	6.3.7, 7.0.3, 7.1.7, 7.2.4
Crucible	4.9.15
Fisheye	4.9.15

Organizations unable to patch immediately should remove affected instances from the internet or otherwise restrict them from external network access. Atlassian provides a Web Application Firewall or proxy rule for all affected products, a Tomcat RewriteValve mitigation for Confluence, Jira Service Management, Jira Software, Bamboo, and Crowd, and a separate urlrewrite.xml rule for Bitbucket. These mitigations are limited and are not replacements for patching.

Rapid7 strongly recommends looking for signs of compromise even after the patch has been applied. Atlassian recommends URL-decoding each access-log request line up to twice, then searching for .. immediately adjacent to /, \, or ::. Alternatively, search raw logs with the vendor-supplied regex:

(?is).*(?:/|\\|::|%(?:25)*(?:2f|5c)|(?::|%(?:25)*3a){2})(?:\.|%(?:25)*2e){2}(?:/|\\|::|%(?:25)*(?:2f|5c)|(?::|%(?:25)*3a){2}|;|%(?:25)*3b|$).*

Public testing artifacts for Jira, Confluence, and Bitbucket include a Python file-read PoC and a Nuclei template. If investigation identifies access to protected configuration files, organizations should rotate exposed credentials and other secrets after containing the affected systems.

For the latest mitigation and investigation guidance, please refer to the vendor security advisory.

Rapid7 customers

Exposure Command, Vulnerability Management, and Nexpose

Exposure Command, Vulnerability Management, and Nexpose customers can assess exposure to CVE-2026-21589 with unauthenticated vulnerability checks on Jira Software Data Center available in the October 8 content release.

Updates

• October 7, 2026: Initial publication.

• October 8, 2026: Updated Rapid7 Customers section to reflect availability of vulnerability checks.

AI is rapidly becoming essential for defenders. But adding AI to a security stack doesn't automatically make security better.

Overview

On September 30, 2026, Cisco published a security advisory for CVE-2026-76504, a critical API authentication bypass vulnerability affecting Cisco Catalyst SD-WAN Manager. The vulnerability has a CVSSv3.1 score of 9.8 and results from improper handling of URL encoding (CWE-177). An unauthenticated, remote attacker can send a crafted HTTP request that bypasses an authentication rule for a specific API endpoint, gaining access to the API with the privileges of the admin user.

According to Cisco, CVE-2026-76504 is being actively exploited in the wild; Cisco PSIRT became aware of the activity in September 2026. Cisco Catalyst SD-WAN Manager systems with ports exposed to the internet are at risk of compromise. The vulnerability affects the product regardless of system configuration, and Cisco has not provided a workaround, however vendor supplied updates are available. Rapid7 strongly recommends that organizations upgrade affected systems to a fixed release on an emergency basis, outside of normal patch cycles, and investigate internet-facing systems for signs of exploitation.

Cisco Catalyst SD-WAN Manager was also affected by two critical, unauthenticated peering authentication flaws earlier in 2026: CVE-2026-20127 and Rapid7-discovered CVE-2026-20182. Both were distinct issues in the vdaemon service and similar parts of its networking stack. CVE-2026-76504 targets a separate API authentication path, but the recurrence of authentication bypasses in internet-facing Catalyst SD-WAN control components reinforces the need for emergency remediation.

On September 30, 2026, CVE-2026-76504 was added to the U.S. Cybersecurity and Infrastructure Security Agency's (CISA) list of known exploited vulnerabilities (KEV), based on evidence of active exploitation. CISA set a remediation due date of October 3, 2026.

Mitigation guidance

Cisco has released software updates that remediate CVE-2026-76504. Organizations running affected instances of Cisco Catalyst SD-WAN Manager should upgrade to an appropriate fixed release listed below without waiting for a regular patch cycle:

Cisco Catalyst SD-WAN Software release	First fixed release
Earlier than 20.9	Migrate to a fixed release
20.9	20.9.10.1
20.12	20.12.8.2
20.15	20.15.6.1
20.18	20.18.4.1
26.1	26.1.2.1
26.2	26.2.1

Cisco has addressed the vulnerability in the cloud-based Cisco SD-WAN Cloud (Cisco Managed) release 20.15.605, and indicates that no customer action is required for that service.

There are no workarounds. As a temporary mitigation, Cisco recommends that on-premises customers prevent access to the system from unsecured networks. If internet access is required, restrict access to known, trusted hosts and protect Cisco Catalyst SD-WAN control components behind a filtering device. Cisco indicates that this mitigation is already deployed in Cisco Catalyst SD-WAN Cloud Hosted environments. Organizations should apply updates even when the mitigation is in place.

Because active exploitation has occurred, Rapid7 strongly recommends that organizations audit affected systems for compromise. For help assessing a potentially compromised system, Cisco customers may open a Severity 3 TAC case with CVE-2026-76504 in the title and provide an admin-tech file generated with the request admin-tech command.

For the latest mitigation guidance and release compatibility information, please refer to the vendor's security advisory.

Rapid7 customers

Exposure Command, Vulnerability Management, and Nexpose

Exposure Command, Vulnerability Management, and Nexpose customers can assess exposure to CVE-2026-76504 with vulnerability checks expected to be available in the October 1 content release.

Indicators of compromise

Cisco recommends reviewing the following logs for requests related to j_security_check from unknown or unauthorized IP addresses:

• /var/log/nms/containers/service-proxy/serviceproxy-access.log: Requests with an encoded character in the j_security_check path, such as POST /%6a_security_check HTTP/1.1.

• /var/log/nms/vmanage-server.log: Requests to j_security_check associated with usernames beginning with viptela-reserved-.

The %6a value, which URI-encodes the character j, is only an example. According to Cisco, an attacker can exploit the vulnerability by encoding any single character in the request. The vendor cautions that these log entries can also occur during standard operations and should be evaluated against normal network posture to avoid false positives.

Updates

• September 30, 2026: Initial publication.

• October 1, 2026: Updated to reflect CVE-2026-76504 being added to the CISA KEV list.

Overview

On September 27, 2026, Citrix disclosed eight new vulnerabilities affecting NetScaler ADC and NetScaler Gateway, including two critical remote code execution (RCE) vulnerabilities: CVE-2026-88771 and CVE-2026-88772. Both of these RCE vulnerabilities carry a critical CVSSv4 score of 9.5, and both have been confirmed as being actively exploited in the wild as zero-days prior to the vendor disclosure. 

CVE-2026-88771 affects vulnerable NetScaler deployments in their default configuration, with no additional product features required. The vendor has also indicated that the attack complexity for exploiting CVE-2026-88771 is low, meaning reliable RCE is likely against all vulnerable NetScaler appliances regardless of their configuration. This is especially concerning due to the prevalence of NetScaler appliances.

CVE-2026-88772 is a memory corruption vulnerability and requires the DTLS feature to be enabled on the appliance. The vendor has indicated that the attack complexity is high, meaning achieving reliable exploitation may be more difficult for an attacker than that of CVE-2026-88771.

The U.S. Cybersecurity and Infrastructure Security Agency (CISA) reports active exploitation is occurring globally, and added both CVE-2026-88771 and CVE-2026-88772 to its Known Exploited Vulnerabilities (KEV) catalog on September 27, 2026. Multiple CERTs worldwide have begun issuing alerts due to the critical nature of this situation.

On October 4, 2026, Citrix published an advisory for a new NetScaler vulnerability, CVE-2026-88779. This new vulnerability was disclosed as being exploited in-the-wild as a zero-day prior to disclosure, and was added to CISA KEV the same day. CVE-2026-88779 affects NetScaler appliances that have a SAML service provider (SP) or identity provider (IdP) configured. Attackers can send repeated attempts, where each attempt will crash the SAML service, and upon the sixth crash the appliance will reboot.

The following table summarizes all nine vulnerabilities:

CVE	CVSSv4	Vulnerability	Exploitation confirmed
CVE-2026-88771	9.5 (Critical)	Improper input validation leading to RCE in a default configuration (CWE-20)	Yes (CISA)
CVE-2026-88772	9.5 (Critical)	Memory overflow leading to RCE in a DTLS configuration (CWE-119)	Yes (CISA)
CVE-2026-88773	9.3 (Critical)	HTTP request smuggling (CWE-444)	No
CVE-2026-88774	7.0 (High)	Policy bypass involving URL expressions (CWE-16)	No
CVE-2026-88775	8.8 (High)	Memory overflow in Gateway or AAA configuration (CWE-119)	No
CVE-2026-88776	8.8 (High)	Memory overflow in load balancer of type Oracle configuration (CWE-119)	No
CVE-2026-88777	8.8 (High)	Memory overflow in a LB/CS or CGNAT-LSN/NAT64 configuration (CWE-119)	No
CVE-2026-88778	8.8 (High)	Predictable TCP initial sequence numbers (CWE-342)	No
CVE-2026-88779	8.7 (High)	Memory overflow in SAML processing (CWE-119)	Yes (CISA)

Mitigation guidance

The following vendor-supplied updates are available to remediate the eight vulnerabilities disclosed on September 27. Rapid7 strongly recommends updating affected NetScaler appliances on an emergency basis, outside of normal patching cycles, and investigating vulnerable appliances for signs of compromise.

• Citrix NetScaler ADC and Citrix NetScaler Gateway 14.1-73.37 and later releases.

• Citrix NetScaler ADC and Citrix NetScaler Gateway 13.1-64.23 and later releases of 13.1.

• Citrix NetScaler ADC 14.1-FIPS, 14.1-73.37 FIPS and later releases of 14.1-FIPS.

• Citrix NetScaler ADC 13.1-FIPS and 13.1-NDcPP 13.1.37.279 and later releases of 13.1-FIPS and 13.1-NDcPP.

For the latest mitigation guidance, please refer to the vendor advisory.

To remediate CVE-2026-88779 which was disclosed on October 4, the following vendor-supplied update is available, and supersedes the above vendor supplied updates.

• Citrix NetScaler ADC and Citrix NetScaler Gateway 14.1-73.41 and later releases.

• Citrix NetScaler ADC and Citrix NetScaler Gateway 13.1-64.28 and later releases of 13.1.

• Citrix NetScaler ADC 14.1-FIPS, 14.1-73.41 FIPS and later releases of 14.1-FIPS.

• Citrix NetScaler ADC 13.1-FIPS and 13.1-NDcPP 13.1.37.282 and later releases of 13.1-FIPS and 13.1-NDcPP.

For the latest mitigation guidance for CVE-2026-88779, please refer to the vendor advisory.

Rapid7 MDR observed exploitation

Rapid7 observed the earliest exploitation attempts of CVE-2026-88771 at 2026-09-20T14:28:43 UTC. Only two attempts were seen on September 20, which does not indicate widespread exploitation at that time.

The command injection observed on September 20 is captured below:

Timestamp: 2026-09-20T14:28:43.000Z
Account: wfr
Result: FAILED_BAD_LOGIN
Source_ip: 149.104.78.208
Source_data: "Authentication is rejected for WFR pitboss PPE nsppe missed too many heartbeats NSPPE;tar${IFS}czf$IFS/var/netscaler/gui/vpn/c$IFS-C$IFS/flash${IFS}nsconfig; (client ip : 149.104.78.208 , vserver ip: <redacted>  ), extended error, if any : "

This payload executes tar czf /var/netscaler/gui/vpn/c -C /flash nsconfig, which creates a gzipped archive named c in /var/netscaler/gui/vpn/ containing the full contents of /flash/nsconfig.

This location is significant because the Gateway serves /var/netscaler/gui/vpn/ publicly at https://<gateway>/vpn/. Once the command runs, an unauthenticated request to GET https://<gateway>/vpn/c will return the archive to any requester, with no login required.

The /flash/nsconfig directory contains material that would give an attacker significant follow-on access, including:

• ns.conf, the full device configuration, including encrypted passwords for the nsroot account and other admin accounts, as well as bind passwords for LDAP, RADIUS, and TACACS

• ssl/, containing SSL certificates and private keys

• SSH host keys, license files, and HA sync settings

As of this writing, Rapid7 has identified two organizations compromised through exploitation of CVE-2026-88771. The first compromise involved the command injection detailed above and the other involved a webshell placed at /var/netscaler/logon/LogonPoint/custom/.ctxs.receiver (SHA256: ed082f744f035035900f67edf438f2f7d0528ac501234f63d476d65273cdb9a1), observed on September 24.

Rapid7 customers

Exposure Command, InsightVM, and Nexpose

Exposure Command, InsightVM, and Nexpose customers can assess exposure to all the CVEs listed in the blog with authenticated vulnerability checks available in the September 28 content release. A vulnerability check for CVE-2026-88779 is available in the October 6 content release.

Intelligence Hub

Customers leveraging Rapid7’s Intelligence Hub can track the latest developments surrounding CVE-2026-88771 and CVE-2026-88772, including indicators of compromise (IOCs) and Suricata detection rules.

Managed Detection Response (MDR)

The following detection rules are available for InsightIDR and Managed Detection Response (MDR) customers:

• Suspicious Web Request -  Citrix NetScaler ADC and Gateway Appliance Exploitation (CVE-2026-88771)

Updates

• September 28, 2026: Initial publication.

• September 29, 2026: Suricata detection rules for CVE-2026-88771 are now available in Intelligence Hub.

• September 30, 2026: Added Rapid7 MDR Observed Exploitation section to include details of the cases flagged by the SOC team.

• September 30, 2026: Added Rapid7 MDR customers section.

• October 5, 2026: Updated blog to include the new CVE-2026-88779 vulnerability.
• October 6, 2026: Updated Rapid7 customers section to reflect availability of a check for CVE-2026-88779.

A user opens a browser tab, pastes data into a chat assistant, and nothing is installed. A developer adds a coding assistant as an editor extension, and nothing shows up in the installed programs list. Someone downloads a local model runtime, a program that runs models directly on the machine instead of sending data to an external service, because they were told not to send company data outside.

Overview

On September 22, 2026, F5 published a security advisory for CVE-2026-94127, a critical heap-based buffer overflow vulnerability affecting F5 BIG-IP Access Policy Manager (APM). The vulnerability has a CVSS v3.1 score of 9.8. An unauthenticated attacker with network access to an affected virtual server may be able to achieve remote code execution (RCE) by sending specifically crafted traffic.

BIG-IP APM provides identity-aware access control for applications and other corporate resources and can integrate with authentication technologies including OAuth, OpenID Connect, and SAML. CVE-2026-94127 is not exposed in a default configuration: exploitation requires a BIG-IP virtual server with both an APM access policy and an OAuth profile configured. Because affected BIG-IP systems may process traffic at an organization's network edge, organizations using this configuration should prioritize remediation.

The vulnerability affects the data plane and does not expose the BIG-IP control plane. BIG-IP systems operating in Appliance mode are also affected.

F5 lists the following affected release trains and corresponding fixed hotfixes:

• BIG-IP 21.1.0: versions prior to Hotfix-BIGIP-21.1.0.2.0.30.22-ENG

• BIG-IP 17.5.0: versions prior to Hotfix-BIGIP-17.5.1.9.0.160.12-ENG

• BIG-IP 17.1.0: versions prior to Hotfix-BIGIP-17.1.3.5.0.41.14-ENG

As of September 22, 2026, CVE-2026-94127 has been added to the CISA KEV while a publicly available proof of concept was not confirmed.

Mitigation guidance

Organizations running affected F5 BIG-IP deployments should apply the appropriate F5 hotfix as soon as operationally feasible, particularly where a vulnerable APM and OAuth configuration is reachable from untrusted networks.

F5 lists the following remediation versions:

• BIG-IP 21.1.0: update to Hotfix-BIGIP-21.1.0.2.0.30.22-ENG or later.

• BIG-IP 17.5.0: update to Hotfix-BIGIP-17.5.1.9.0.160.12-ENG or later.

• BIG-IP 17.1.0: update to Hotfix-BIGIP-17.1.3.5.0.41.14-ENG or later.

Administrators should first determine whether a BIG-IP APM access policy and an OAuth profile are configured together on a virtual server, since this configuration is required for exposure.

For organizations that cannot immediately apply the applicable update, F5 provides an iRule workaround through F5 Support. Customers should open a support case with F5 to obtain the vendor-provided workaround and follow F5's implementation guidance.

Rapid7 customers

Exposure Command, Vulnerability Management, and Nexpose

Exposure Command, Vulnerability Management, Nexpose customers can assess exposure to CVE-2026-94127 using vulnerability checks expected to be available in today’s (September 23) content release.

Updates

• September 22, 2026: Initial publication.

Cybersecurity spent the past decade learning to assume the breach. AI is forcing the industry to reconsider what must happen before one. 

Bitdefender rolled out new functionality in Bitdefender GravityZone, a unified cybersecurity platform that provides prevention, protection, detection, and response capabilities for organizations of all sizes.  These features, consistent with our multi-layered security strategy, are intended to ease the workload of security analysts, administrators, and users.