CVE-2026-20249 PUBLISHED

Cisco Secure Firewall Adaptive Security Appliance and Secure Firewall Threat Defense Software IKEv2 Certificate Authentication Denial of Service Vulnerability

Assigner: cisco
Reserved: 08.10.2025 Published: 16.09.2026 Updated: 16.09.2026

A vulnerability in the certification authentication feature of Internet Key Exchange version 2 (IKEv2) for Cisco Secure Firewall Adaptive Security Appliance (ASA) Software and Cisco Secure Firewall Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause an affected device to reload unexpectedly.

This vulnerability is due to a logic error during the certificate authentication phase of the IKEv2 connection setup. An attacker could exploit this vulnerability by attempting to establish an IKEv2 VPN connection with a crafted certificate. A successful exploit could allow the attacker to cause the IKEv2 process to crash, causing a denial of service (DoS) condition.

Metrics

CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
CVSS Score: 8.6

Product Status

Vendor Cisco
Product Cisco Secure Firewall Adaptive Security Appliance (ASA) Software
Versions Default: unknown
  • Version 9.16.1 is affected
  • Version 9.16.1.28 is affected
  • Version 9.16.2 is affected
  • Version 9.16.2.3 is affected
  • Version 9.16.2.7 is affected
  • Version 9.16.2.11 is affected
  • Version 9.16.2.13 is affected
  • Version 9.16.2.14 is affected
  • Version 9.16.3.3 is affected
  • Version 9.16.3 is affected
  • Version 9.16.3.14 is affected
  • Version 9.18.1 is affected
  • Version 9.16.3.15 is affected
  • Version 9.18.1.3 is affected
  • Version 9.18.2 is affected
  • Version 9.16.3.19 is affected
  • Version 9.16.3.23 is affected
  • Version 9.18.2.5 is affected
  • Version 9.16.4 is affected
  • Version 9.18.2.7 is affected
  • Version 9.19.1 is affected
  • Version 9.16.4.9 is affected
  • Version 9.18.2.8 is affected
  • Version 9.16.4.14 is affected
  • Version 9.18.3 is affected
  • Version 9.19.1.5 is affected
  • Version 9.16.4.18 is affected
  • Version 9.19.1.9 is affected
  • Version 9.18.3.39 is affected
  • Version 9.16.4.19 is affected
  • Version 9.19.1.12 is affected
  • Version 9.18.3.46 is affected
  • Version 9.16.4.27 is affected
  • Version 9.19.1.18 is affected
  • Version 9.18.3.53 is affected
  • Version 9.18.3.55 is affected
  • Version 9.16.4.38 is affected
  • Version 9.16.4.39 is affected
  • Version 9.18.3.56 is affected
  • Version 9.20.1 is affected
  • Version 9.16.4.42 is affected
  • Version 9.19.1.22 is affected
  • Version 9.18.4 is affected
  • Version 9.20.1.5 is affected
  • Version 9.18.4.5 is affected
  • Version 9.19.1.24 is affected
  • Version 9.16.4.48 is affected
  • Version 9.18.4.8 is affected
  • Version 9.20.2 is affected
  • Version 9.19.1.27 is affected
  • Version 9.16.4.55 is affected
  • Version 9.18.4.22 is affected
  • Version 9.20.2.10 is affected
  • Version 9.16.4.57 is affected
  • Version 9.19.1.28 is affected
  • Version 9.18.4.24 is affected
  • Version 9.20.2.21 is affected
  • Version 9.16.4.61 is affected
  • Version 9.19.1.31 is affected
  • Version 9.18.4.29 is affected
  • Version 9.20.2.22 is affected
  • Version 9.16.4.62 is affected
  • Version 9.18.4.34 is affected
  • Version 9.20.3 is affected
  • Version 9.16.4.67 is affected
  • Version 9.16.4.70 is affected
  • Version 9.18.4.40 is affected
  • Version 9.23.1 is affected
  • Version 9.22.1.1 is affected
  • Version 9.16.4.71 is affected
  • Version 9.20.3.4 is affected
  • Version 9.18.4.47 is affected
  • Version 9.20.3.7 is affected
  • Version 9.19.1.37 is affected
  • Version 9.16.4.76 is affected
  • Version 9.20.3.9 is affected
  • Version 9.19.1.38 is affected
  • Version 9.18.4.50 is affected
  • Version 9.22.1.3 is affected
  • Version 9.20.3.10 is affected
  • Version 9.22.1.2 is affected
  • Version 9.18.4.52 is affected
  • Version 9.20.3.13 is affected
  • Version 9.22.1.6 is affected
  • Version 9.18.4.53 is affected
  • Version 9.16.4.82 is affected
  • Version 9.22.2 is affected
  • Version 9.20.3.16 is affected
  • Version 9.19.1.42 is affected
  • Version 9.18.4.57 is affected
  • Version 9.16.4.84 is affected
  • Version 9.23.1.3 is affected
  • Version 9.20.3.20 is affected
  • Version 9.22.2.4 is affected
  • Version 9.23.1.7 is affected
  • Version 9.20.4 is affected
  • Version 9.22.2.9 is affected
  • Version 9.23.1.13 is affected
  • Version 9.20.4.7 is affected
  • Version 9.22.2.13 is affected
  • Version 9.18.4.66 is affected
  • Version 9.20.4.10 is affected
  • Version 9.23.1.19 is affected
  • Version 9.16.4.85 is affected
  • Version 9.22.2.14 is affected
  • Version 9.18.4.67 is affected
  • Version 9.24.1 is affected
  • Version 9.18.4.68 is affected
  • Version 9.23.1.22 is affected
  • Version 9.20.4.14 is affected
  • Version 9.22.2.20 is affected
  • Version 9.18.4.71 is affected
  • Version 9.20.4.19 is affected
  • Version 9.23.1.26 is affected
  • Version 9.16.4.89 is affected
  • Version 9.22.2.32 is affected
  • Version 9.18.4.76 is affected
  • Version 9.22.3 is affected
  • Version 9.24.1.5 is affected
  • Version 9.20.4.22 is affected
  • Version 9.24.1.9 is affected
  • Version 9.20.4.28 is affected
  • Version 9.16.4.92 is affected
  • Version 9.18.4.135 is affected
  • Version 9.23.1.195 is affected
  • Version 9.20.4.30 is affected
  • Version 9.24.1.155 is affected
  • Version 9.23.1.32 is affected
  • Version 9.18.4.82 is affected
Vendor Cisco
Product Cisco Secure Firewall Threat Defense (FTD) Software
Versions Default: unknown
  • Version 7.0.0 is affected
  • Version 7.0.0.1 is affected
  • Version 7.0.1 is affected
  • Version 7.0.1.1 is affected
  • Version 7.0.2 is affected
  • Version 7.2.0 is affected
  • Version 7.0.2.1 is affected
  • Version 7.0.3 is affected
  • Version 7.2.0.1 is affected
  • Version 7.0.4 is affected
  • Version 7.2.1 is affected
  • Version 7.0.5 is affected
  • Version 7.3.0 is affected
  • Version 7.2.2 is affected
  • Version 7.2.3 is affected
  • Version 7.3.1 is affected
  • Version 7.2.4 is affected
  • Version 7.0.6 is affected
  • Version 7.2.5 is affected
  • Version 7.2.4.1 is affected
  • Version 7.3.1.1 is affected
  • Version 7.4.0 is affected
  • Version 7.0.6.1 is affected
  • Version 7.2.5.1 is affected
  • Version 7.4.1 is affected
  • Version 7.2.6 is affected
  • Version 7.0.6.2 is affected
  • Version 7.4.1.1 is affected
  • Version 7.2.7 is affected
  • Version 7.2.5.2 is affected
  • Version 7.3.1.2 is affected
  • Version 7.2.8 is affected
  • Version 7.6.0 is affected
  • Version 7.4.2 is affected
  • Version 7.2.8.1 is affected
  • Version 7.0.6.3 is affected
  • Version 7.4.2.1 is affected
  • Version 7.2.9 is affected
  • Version 7.0.7 is affected
  • Version 7.7.0 is affected
  • Version 7.4.2.2 is affected
  • Version 7.2.10 is affected
  • Version 7.6.1 is affected
  • Version 7.4.2.3 is affected
  • Version 7.0.8 is affected
  • Version 7.6.2 is affected
  • Version 7.7.10 is affected
  • Version 7.7.11 is affected
  • Version 7.0.8.1 is affected
  • Version 7.6.2.1 is affected
  • Version 7.7.10.1 is affected
  • Version 7.4.2.4 is affected
  • Version 7.2.10.2 is affected
  • Version 7.4.3 is affected
  • Version 7.6.4 is affected
  • Version 10.0.0 is affected
  • Version 7.4.4 is affected
  • Version 7.0.9 is affected
  • Version 7.2.11 is affected
  • Version 7.4.7 is affected

Exploits

The Cisco Product Security Incident Response Team (PSIRT) is not aware of any public announcements or malicious use of the vulnerability that is described in this advisory.

References

Problem Types

  • Incorrect Type Conversion or Cast cwe