High [CVE-2026-76418] Cisco Secure Firewall Adaptive Security Appliance and Secure Firewall Threat Defense Software Remote Access SSL VPN Tunnel Denial of Service Vulnerability
This high-severity Cisco advisory covers CVE-2026-76418 affecting Secure Firewall Adaptive Security Appliance (ASA) Software, Firepower 2100 Series, Firepower 1000 Series.
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Summary
A vulnerability in the Remote Access SSL VPN service 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 the device to reload unexpectedly, resulting in a denial of service (DoS) condition.
This vulnerability is due to logic errors when secondary authentication is configured on a tunnel group. An attacker could exploit this vulnerability by sending a crafted request when connecting to the SSL remote access VPN.
Cisco has released software updates that address this vulnerability. There are no workarounds that address this vulnerability.
Affected products named by the advisory: Firepower 2100 Series; Firepower 1000 Series; ASA 5500-X Series Firewalls; 3000 Series Industrial Security Appliances (ISA); and 3 more.
- Release 9.16 and earlier (first fixed: 9.16.4.104)
- Release 9.18 (first fixed: 9.18.4.96)
- Release 9.20 (first fixed: 9.20.4.50)
- Release 9.22 (first fixed: 9.22.3.200)
- Release 9.23 (first fixed: 9.23.1.48)
- Release 9.24 (first fixed: 9.24.1.27)
- Release 7.0 and earlier (first fixed: 7.0.11)
- Release 7.2 (first fixed: 7.2.13)
- Release 7.4 (first fixed: 7.4.9)
- Release 7.6 (first fixed: 7.6.7)
- Release 7.7 (first fixed: 7.7.14)
- Release 10.0 (first fixed: 10.0.3)
- Release 10.1 (first fixed: 10.1.1)
Official advisory · high-confidence parse· fetched 15 hours ago·verify at source
- 9.16.4.104
- 9.18.4.96
- 9.20.4.50
- 9.22.3.200
- 9.23.1.48
- 9.24.1.27
- 7.0.11
- 7.2.13
- 7.4.9
- 7.6.7
- 7.7.14
- 10.0.3
- 10.1.1
Official advisory · high-confidence parse· fetched 15 hours ago·verify at source
Mitigation checklist
- Upgrade to the first fixed release for your train per the Fixed Releases table in this advisory.
- Release 9.16 and earlier: upgrade to 9.16.4.104.
- Release 9.18: upgrade to 9.18.4.96.
- Release 9.20: upgrade to 9.20.4.50.
- Release 9.22: upgrade to 9.22.3.200.
- Release 9.23: upgrade to 9.23.1.48.
- Release 9.24: upgrade to 9.24.1.27.
- Release 7.0 and earlier: upgrade to 7.0.11.
- Release 7.2: upgrade to 7.2.13.
- There are no workarounds that address this vulnerability. However, there is a mitigation, which is to disable secondary authentication on any user-configured tunnel group list or on the default tunnel group, DefaultWEBVPNGroup.
- Case 1: If DefaultWEBVPNGroup does not use secondary authentication, disable the tunnel group list. In WebVPN configuration mode, enter no tunnel-group-list enable. With the tunnel group list disabled, users will no longer be able to choose a connection profile (the tunnel-group name) from a provided list and instead will need to know the correct profile to use.
- Case 2: If DefaultWEBVPNGroup uses secondary authentication, use the no secondary-authentication-server-group CLI command to remove secondary authentication. With secondary authentication disabled, the security posture is lowered for remote access VPN.
Official advisory · high-confidence parse· fetched 15 hours ago·verify at source
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