CVEvulnerability

CVE-2026-20349

8.6 HIGH Known exploited Published 2026-08-11 Modified 2026-10-26 Official page ↗

CISA Known Exploited Vulnerability

Cisco Secure Firewall Adaptive Security Appliance (ASA) and Secure Firewall Threat Defense (FTD) Heap Inspection Vulnerability — Cisco Secure Firewall Adaptive Security Appliance (ASA) and Secure Firewall Threat Defense (FTD)

Cisco Secure Firewall Adaptive Security Appliance (ASA) and Secure Firewall Threat Defense (FTD) contain a heap inspection vulnerability that could allow an unauthenticated, remote attacker to cause the device to reload unexpectedly, resulting in a denial of service (DoS) condition.

Added to KEV
2026-08-11
Remediation due
2026-08-14
Ransomware use
Unknown
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.
Notes
https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-asaftd-vpn-dos-dzv4mQFF ; BOD 26-04: https://www.cisa.gov/news-events/directives/bod-26-04-prioritizing-security-updates-based-risk ; Forensics Triage Requirements: https://www.cisa.gov/news-events/directives/bod-26-04-implementation-guidance-prioritizing-security-updates-based-risk ; https://nvd.nist.gov/vuln/detail/CVE-2026-20349
Status
Analyzed
Published
2026-08-11
Last modified
2026-10-26
Assigner
[email protected]
CVSS 3.1 ([email protected])
8.6 HIGH — CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
Weaknesses
CWE-244

Description

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.

Affected configurations

• cisco adaptive security appliance software 9.16.1 • cisco adaptive security appliance software 9.16.1.28 • cisco adaptive security appliance software 9.16.2 • cisco adaptive security appliance software 9.16.2.3 • cisco adaptive security appliance software 9.16.2.7 • cisco adaptive security appliance software 9.16.2.11 • cisco adaptive security appliance software 9.16.2.13 • cisco adaptive security appliance software 9.16.2.14 • cisco adaptive security appliance software 9.16.3 • cisco adaptive security appliance software 9.16.3.3 • cisco adaptive security appliance software 9.16.3.14 • cisco adaptive security appliance software 9.16.3.15 • cisco adaptive security appliance software 9.16.3.19 • cisco adaptive security appliance software 9.16.3.23 • cisco adaptive security appliance software 9.16.4 • cisco adaptive security appliance software 9.16.4.9 • cisco adaptive security appliance software 9.16.4.14 • cisco adaptive security appliance software 9.16.4.19 • cisco adaptive security appliance software 9.16.4.27 • cisco adaptive security appliance software 9.16.4.38 • cisco adaptive security appliance software 9.16.4.39 • cisco adaptive security appliance software 9.16.4.42 • cisco adaptive security appliance software 9.16.4.48 • cisco adaptive security appliance software 9.16.4.55 • cisco adaptive security appliance software 9.16.4.57 • cisco adaptive security appliance software 9.16.4.61 • cisco adaptive security appliance software 9.16.4.62 • cisco adaptive security appliance software 9.16.4.67 • cisco adaptive security appliance software 9.16.4.70 • cisco adaptive security appliance software 9.16.4.71 • cisco adaptive security appliance software 9.16.4.76 • cisco adaptive security appliance software 9.16.4.82 • cisco adaptive security appliance software 9.16.4.84 • cisco adaptive security appliance software 9.16.4.85 • cisco adaptive security appliance software 9.16.4.89 • cisco adaptive security appliance software 9.16.4.92 • cisco adaptive security appliance software 9.18.1 • cisco adaptive security appliance software 9.18.1.3 • cisco adaptive security appliance software 9.18.2 • cisco adaptive security appliance software 9.18.2.5 • cisco adaptive security appliance software 9.18.2.7 • cisco adaptive security appliance software 9.18.2.8 • cisco adaptive security appliance software 9.18.3 • cisco adaptive security appliance software 9.18.3.39 • cisco adaptive security appliance software 9.18.3.46 • cisco adaptive security appliance software 9.18.3.53 • cisco adaptive security appliance software 9.18.3.55 • cisco adaptive security appliance software 9.18.3.56 • cisco adaptive security appliance software 9.18.4 • cisco adaptive security appliance software 9.18.4.5 • cisco adaptive security appliance software 9.18.4.8 • cisco adaptive security appliance software 9.18.4.22 • cisco adaptive security appliance software 9.18.4.24 • cisco adaptive security appliance software 9.18.4.29 • cisco adaptive security appliance software 9.18.4.34 • cisco adaptive security appliance software 9.18.4.40 • cisco adaptive security appliance software 9.18.4.47 • cisco adaptive security appliance software 9.18.4.50 • cisco adaptive security appliance software 9.18.4.52 • cisco adaptive security appliance software 9.18.4.53 … and 137 more

Related

Weakness · CWE (1)

  • CWE-244 Improper Clearing of Heap Memory Before Release weakness

References