Cisco Secure Firewall Adaptive Security Appliance (ASA) and Secure Firewall Threat Defense (FTD) Heap Inspection Vulnerability
Cisco — Cisco Secure Firewall Adaptive Security Appliance (ASA) Software
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 attacker to cause the affected device to reload, resulting in a DoS condition.
8.6
2.2%
Vector breakdown
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- None
- User interaction
- None
- Scope
- Changed
- Confidentiality
- None
- Integrity
- None
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
- Published
- Aug 11, 2026
- Modified
- Aug 12, 2026
- Added to KEV
- Aug 11, 2026
- Federal patch due
- Aug 14, 2026
CISA required action
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.
Weakness classification
Affected packages
Proof-of-concept & exploitation references
Weaponization
Public repositories whose name or description references CVE-2026-20349, found via a live GitHub search at request time. These are community-sourced signals, not a verified working exploit - cross-check each one before relying on it, and treat higher star counts and recent activity as (weak) corroboration, not proof.
No public GitHub repositories referencing CVE-2026-20349 were found at last check. Absence here is not proof no exploit exists - see the references below for vendor advisories and write-ups.
References
Frequently asked questions
What is CVE-2026-20349?
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 attacker to cause the affected device to reload, resulting in a DoS condition.
How severe is CVE-2026-20349?
CVE-2026-20349 has a CVSS base score of 8.6 out of 10 (CVSS 3.1).
Is CVE-2026-20349 actively exploited in the wild?
Yes. CVE-2026-20349 is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog, added Aug 11, 2026, meaning CISA has confirmed evidence of active exploitation.
What is the EPSS score for CVE-2026-20349?
2.2% - meaning FIRST.org's EPSS model estimates a 2.2% probability this vulnerability will be exploited in the wild within 30 days (81% percentile among all scored CVEs).
What type of vulnerability is CVE-2026-20349?
CVE-2026-20349 is classified under CWE-244 (Improper Clearing of Heap Memory Before Release ('Heap Inspection')).
Cross-checked against
Impactr finds and proves whether CVE-2026-20349 - or flaws like it - are actually reachable in your own web apps and APIs, with a reproducible exploit as evidence.
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