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
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.
Weakness: CWE-401
Affected products
| Vendor | Product | Category | Matched by |
|---|---|---|---|
| Cisco | Cisco Adaptive Security Appliance (ASA) Check your version | Firewall / NGFW | cna-assigner |
| Cisco | Cisco Firepower Threat Defense (FTD) Check your version | Firewall / NGFW | cna-assigner |
Vendor-reported products (2)
- Cisco · Cisco Adaptive Security Appliance (ASA) Software
- Cisco · Cisco Firepower Threat Defense Software
Vendor advisory
cisco-sa-asaftd-vpn-dos-mfPekA6e
Cisco Secure Firewall Adaptive Security Appliance and Secure Firewall Threat Defense Software Remote Access SSL VPN Denial of Service Vulnerabilities
Cisco’s rating: High (advisory CVSS 8.6) · Published Aug 14, 2025
Bug IDs: CSCwk44165 , CSCwo15027
The vendor’s rating applies to the whole advisory and can differ from this CVE’s own CVSS severity. Where this comes from