Cisco ASA/FTD IKEv2 Cert Auth Logic Error Causing DoS
CVE-2026-20249 Published on September 16, 2026

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

NVD

Vulnerability Analysis

CVE-2026-20249 can be exploited with network access, and does not require authorization privileges or user interaction. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to have no impact on confidentiality and integrity, and a high impact on availability.

Attack Vector:
NETWORK
Attack Complexity:
LOW
Privileges Required:
NONE
User Interaction:
NONE
Scope:
CHANGED
Confidentiality Impact:
NONE
Integrity Impact:
NONE
Availability Impact:
HIGH

Weakness Type

Incorrect Type Conversion or Cast

The software does not correctly convert an object, resource, or structure from one type to a different type.


Products Associated with CVE-2026-20249

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Cisco Adaptive Security Appliance
 

Affected Versions

Cisco Secure Firewall Adaptive Security Appliance (ASA) Software: Cisco Secure Firewall Threat Defense (FTD) Software: