How severe is CVE-2026-20349?

CVE-2026-20349 has a CVSS score of 8.6/10, rated HIGH. Immediate patching is strongly recommended.

Which packages are affected by CVE-2026-20349?

Affected package information for CVE-2026-20349 is not yet fully mapped. Check the official advisory links for details.

How do I fix CVE-2026-20349?

The records we use list no fixed release for CVE-2026-20349. Check the upstream advisory for a patched version, and apply the exposure-reduction steps below in the meantime.

How do I detect CVE-2026-20349 in my code and dependencies?

Identify every host running the affected component and compare the installed build against the fixed version below — for source-built or distro-packaged software the version string, not a lockfile, is the source of truth (`dpkg -l`, `rpm -q`, or the binary's own `--version`).

How do I mitigate CVE-2026-20349 if there is no patch (or I can't update yet)?

Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service.

Is CVE-2026-20349 actively exploited in the wild?

No public exploit code has been indexed for CVE-2026-20349 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2026-20349?

CVE-2026-20349 has an EPSS (Exploit Prediction Scoring System) score of 1.0%, placing it in the 63th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

Is CVE-2026-20349 in the CISA Known Exploited Vulnerabilities catalog?

Yes. CVE-2026-20349 (Cisco Secure Firewall Adaptive Security Appliance (ASA) and Secure Firewall Threat Defense (FTD) Heap Inspection Vulnerability) was added to CISA's Known Exploited Vulnerabilities (KEV) catalog on 2026-08-11. CISA required all US federal civilian agencies to remediate this vulnerability by 2026-08-14. The required action was: Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines. Being listed in the KEV catalog is the strongest possible confirmation of active exploitation — treat this as a critical priority.

What type of vulnerability is CVE-2026-20349?

CVE-2026-20349 is classified as CWE-244 (CWE-244). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2026-20349 published, and has it been updated?

CVE-2026-20349 was published on August 11, 2026 and was last updated on September 16, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🛡️

CISA KEV · ACTIVELY EXPLOITED

HIGH severity

CVE-2026-20349

HIGH

CVE-2026-20349 is a high-severity (CVSS 8.6) CWE-244 vulnerability. It is in CISA's Known Exploited Vulnerabilities catalog (added 2026-08-11) — treat it as actively exploited and patch now. The records list no fixed version yet; check the vendor advisory below and apply the mitigations in the meantime.

A vulnerability in the Remote Access SSL VPN service for Cisco Secure Firewall Adaptive Security Appliance (ASA) Software and Cisco Secure Firewall Threat Defense (FTD) Software could…

Published

Aug 11, 2026

Updated

Sep 16, 2026

Affected

2 products

Patched

See advisory

Exploits

None indexed

Exploitation data as of Nov 10, 2026 · OSV.dev, NVD, CISA KEV, FIRST.org (EPSS)

Exploitation Status

Actively exploited in the wild

Confirmed by CISA's Known Exploited Vulnerabilities catalog on 2026-08-11. Federal agencies were required to remediate by 2026-08-14.
CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.

Exploitation and automatability from CISA (KEV catalog and SSVC triage) for CVE-2026-20349.

EPSS Exploitation Probability

via FIRST.org ↗

1.0%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs63th percentile — riskier than 63% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

Where this sits among everything scored

Description

This vulnerability is due to insufficient error checking when processing HTTP requests. An attacker could exploit this vulnerability by sending a crafted HTTP request to the Remote Access SSL VPN service on an affected device. A successful exploit could allow the attacker to cause the affected device to reload, resulting in a DoS condition.

Affected Products

2 products · 197 configurations

adaptive security appliance softwarecisco

133 versions

9.16.19.16.1.289.16.29.16.2.39.16.2.79.16.2.119.16.2.139.16.2.149.16.39.16.3.39.16.3.149.16.3.15

Application

secure firewall threat defensecisco

64 versions

7.0.07.0.0.17.0.17.0.1.17.0.27.0.2.17.0.37.0.47.0.57.0.67.0.6.17.0.6.2

Detection & mitigation playbook

Vulnerability

Detect
Identify every host running the affected component and compare the installed build against the fixed version below — for source-built or distro-packaged software the version string, not a lockfile, is the source of truth (`dpkg -l`, `rpm -q`, or the binary's own `--version`).
Remediation status
The records we use list no fixed release for CVE-2026-20349. Check the upstream advisory for a patched version, and apply the exposure-reduction steps below in the meantime.
Mitigate without a patch
Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service.

Frequently Asked Questions

A vulnerability in the Remote Access SSL VPN service for Cisco Secure Firewall Adaptive Security Appliance (ASA) Software and Cisco Secure Firewall Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause the device to reload unexpectedly, resulting in a denial of service (DoS) condition.  This vulnerability is due to insufficient error checking when processing HTTP requests. An attacker could exploit this vulnerability by sending a crafted HTTP request to the Remote Access SSL VPN service on an affected device. A successful exploit could allow the attacke

O3 Security · Impact-Aware SCA

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