CVE-2026-20349

Cisco Secure Firewall Adaptive Security Appliance and Secure Firewall Threat Defense Software Remote Access SSL VPN Denial of Service Vulnerability

CVSS 8.6 high · Cisco Cisco Secure Firewall Adaptive Security Appliance (ASA) Software · published 2026-08-11

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.

NVD · CVE.org

Coverage 2 sources

1. 2026-08-11 CISA Cybersecurity Advisories high CISA Adds Three Known Exploited Vulnerabilities to Catalog

   CISA added three exploited vulnerabilities to its KEV Catalog: Cisco ASA/FTD, Microsoft Windows, and Metabase.

2. 2026-08-13 Help Net Security high Cisco fixes vulnerability exploited to DoS its firewalls (CVE-2026-20349)

   Cisco fixes high-severity vulnerability (CVE-2026-20349) exploited for DoS attacks on firewalls.

Mentioned with

CVE-2026-68820 CVE-2026-72898

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