CVE-2025-20133: Cisco Secure Firewall Adaptive Security Appliance and Secure Firewall Threat Defense Software Remote Access SSL VPN Authentication Targeted Denial of Service Vulnerability
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.
Affected Software
Event History
Frequently Asked Questions
What is the severity of CVE-2025-20133?
CVE-2025-20133 is classified as a denial-of-service vulnerability that affects Cisco Secure Firewall ASA and Secure FTD software.
How do I fix CVE-2025-20133?
To mitigate CVE-2025-20133, ensure that your Cisco Secure Firewall ASA or Secure FTD Software is updated to the latest version provided by Cisco.
Who is affected by CVE-2025-20133?
CVE-2025-20133 impacts organizations using Cisco Secure Firewall ASA Software and Secure FTD Software.
What can an attacker do with CVE-2025-20133?
An unauthenticated remote attacker can exploit CVE-2025-20133 to cause the affected device to become unresponsive, resulting in a denial-of-service condition.
Is CVE-2025-20133 being actively exploited?
As of the latest updates, there have been no reports of active exploitation of CVE-2025-20133, but it is recommended to apply security measures immediately.