Cisco FTD: CVE-2025-20222: Cisco Secure Firewall Adaptive Security Appliance and Secure Firewall Threat Defense Software for Firepower 2100 Series IPv6 over IPsec Denial of Service Vulnerability

A vulnerability in the RADIUS proxy feature for the IPsec VPN feature of Cisco Secure Firewall Adaptive Security Appliance (ASA) Software and Cisco Secure Firewall Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition.

This vulnerability is due to improper processing of IPv6 packets. An attacker could exploit this vulnerability by sending IPv6 packets over an IPsec VPN connection to an affected device. A successful exploit could allow the attacker to trigger a reload of the device, resulting in a DoS condition.