Cisco ASA and FTD VPN Flaw Actively Exploited to Crash Devices

Cisco has issued a warning regarding a high-severity denial-of-service vulnerability, CVE-2026-20349, affecting Secure Firewall ASA and FTD devices. This flaw, with a CVSS score of 8.6, allows attackers to remotely crash devices by sending crafted HTTP requests to the Remote Access SSL VPN service. The vulnerability impacts devices with specific remote access services enabled and can be exploited without authentication. Cisco has confirmed that there are no workarounds available and strongly recommends upgrading to fixed software releases. Active exploitation was detected in August 2026, although details about the attackers or targeted organizations remain undisclosed. Cisco has released hot fixes for several affected software versions, but no indicators of compromise have been provided. The vulnerability was identified during internal security testing and reported by a researcher.

Key Points: • CVE-2026-20349 is a high-severity DoS vulnerability affecting Cisco ASA and FTD devices. • Attackers can exploit the flaw remotely without authentication, leading to device crashes. • Cisco has released hot fixes but no workarounds; active exploitation has been confirmed.