Cisco ASA and FTD Flaw Exploited in the Wild Can Trigger Remote DoS

Ravie LakshmananAug 12, 2026Network Security / Vulnerability

Cisco has warned that a new vulnerability impacting Secure Firewall Adaptive Security Appliance (ASA) Software and Secure Firewall Threat Defense (FTD) Software has been exploited in the wild.

The high-severity flaw, tracked as CVE-2026-20349 (CVSS score: 8.6), is a case of insufficient error checking when processing HTTP requests that could allow an unauthenticated, remote attacker to trigger a denial-of-service (DoS) condition.

“An attacker could exploit this vulnerability by sending a crafted HTTP request to the Remote Access SSL VPN service on an affected device,” Cisco said in a Tuesday advisory. “A successful exploit could allow the attacker to cause the affected device to reload, resulting in a DoS condition.”

The security defects impact devices running a vulnerable version of Secure Firewall ASA Software or Cisco Secure FTD Software and have one or more of the vulnerable configurations listed below –

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