CVE-2025-20133: cisco cisco adaptive security appliance (asa) software

Vulnerability summary

CVE-2025-20133 is a high (CVSS 8.6) vulnerability in cisco cisco adaptive security appliance (asa) software. EPSS estimates a 0.78% chance of exploitation in the next 30 days, higher than 54.9% of scored vulnerabilities.

Timeline

1. 14-08-2025
   PublishedVulnerability first disclosed.
2. 14-08-2025
   Last modifiedVulnerability information updated.

Description

A vulnerability in the management and VPN web servers of the Remote Access SSL VPN feature of Cisco Secure Firewall ASA Software and Secure FTD Software could allow an unauthenticated, remote attacker to cause the device to unexpectedly stop responding, resulting in a DoS condition. This vulnerability is due to ineffective validation of user-supplied input during the Remote Access SSL VPN authentication process. An attacker could exploit this vulnerability by sending a crafted request to the VPN service on an affected device. A successful exploit could allow the attacker to cause a DoS condition where the device stops responding to Remote Access SSL VPN authentication requests.

• CWE-401Missing Release of Memory after Effective LifetimeThe product does not sufficiently track and release allocated memory after it has been used, making the memory unavailable for reallocation and reuse.