CVE-2026-20249

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

View on CVE.org

Published Sep 16, 2026 CVSS 3.1 · 8.6 High EPSS < 1% KEV · Not listed

Description

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.

Affected Products

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor Product Default status Versions

Cisco

Cisco Secure Firewall Adaptive Security Appliance (ASA) Software

unknown

Version	Status	Constraints
`9.16.1`	affected	—
`9.16.1.28`	affected	—
`9.16.2`	affected	—
`9.16.2.3`	affected	—
`9.16.2.7`	affected	—
`9.16.2.11`	affected	—
`9.16.2.13`	affected	—
`9.16.2.14`	affected	—
`9.16.3.3`	affected	—
`9.16.3`	affected	—
`9.16.3.14`	affected	—
`9.18.1`	affected	—
`9.16.3.15`	affected	—
`9.18.1.3`	affected	—
`9.18.2`	affected	—
`9.16.3.19`	affected	—
`9.16.3.23`	affected	—
`9.18.2.5`	affected	—
`9.16.4`	affected	—
`9.18.2.7`	affected	—
`9.19.1`	affected	—
`9.16.4.9`	affected	—
`9.18.2.8`	affected	—
`9.16.4.14`	affected	—
`9.18.3`	affected	—
`9.19.1.5`	affected	—
`9.16.4.18`	affected	—
`9.19.1.9`	affected	—
`9.18.3.39`	affected	—
`9.16.4.19`	affected	—
`9.19.1.12`	affected	—
`9.18.3.46`	affected	—
`9.16.4.27`	affected	—
`9.19.1.18`	affected	—
`9.18.3.53`	affected	—
`9.18.3.55`	affected	—
`9.16.4.38`	affected	—
`9.16.4.39`	affected	—
`9.18.3.56`	affected	—
`9.20.1`	affected	—
`9.16.4.42`	affected	—
`9.19.1.22`	affected	—
`9.18.4`	affected	—
`9.20.1.5`	affected	—
`9.18.4.5`	affected	—
`9.19.1.24`	affected	—
`9.16.4.48`	affected	—
`9.18.4.8`	affected	—
`9.20.2`	affected	—
`9.19.1.27`	affected	—
`9.16.4.55`	affected	—
`9.18.4.22`	affected	—
`9.20.2.10`	affected	—
`9.16.4.57`	affected	—
`9.19.1.28`	affected	—
`9.18.4.24`	affected	—
`9.20.2.21`	affected	—
`9.16.4.61`	affected	—
`9.19.1.31`	affected	—
`9.18.4.29`	affected	—
`9.20.2.22`	affected	—
`9.16.4.62`	affected	—
`9.18.4.34`	affected	—
`9.20.3`	affected	—
`9.16.4.67`	affected	—
`9.16.4.70`	affected	—
`9.18.4.40`	affected	—
`9.23.1`	affected	—
`9.22.1.1`	affected	—
`9.16.4.71`	affected	—
`9.20.3.4`	affected	—
`9.18.4.47`	affected	—
`9.20.3.7`	affected	—
`9.19.1.37`	affected	—
`9.16.4.76`	affected	—
`9.20.3.9`	affected	—
`9.19.1.38`	affected	—
`9.18.4.50`	affected	—
`9.22.1.3`	affected	—
`9.20.3.10`	affected	—
`9.22.1.2`	affected	—
`9.18.4.52`	affected	—
`9.20.3.13`	affected	—
`9.22.1.6`	affected	—
`9.18.4.53`	affected	—
`9.16.4.82`	affected	—
`9.22.2`	affected	—
`9.20.3.16`	affected	—
`9.19.1.42`	affected	—
`9.18.4.57`	affected	—
`9.16.4.84`	affected	—
`9.23.1.3`	affected	—
`9.20.3.20`	affected	—
`9.22.2.4`	affected	—
`9.23.1.7`	affected	—
`9.20.4`	affected	—
`9.22.2.9`	affected	—
`9.23.1.13`	affected	—
`9.20.4.7`	affected	—
`9.22.2.13`	affected	—
`9.18.4.66`	affected	—
`9.20.4.10`	affected	—
`9.23.1.19`	affected	—
`9.16.4.85`	affected	—
`9.22.2.14`	affected	—
`9.18.4.67`	affected	—
`9.24.1`	affected	—
`9.18.4.68`	affected	—
`9.23.1.22`	affected	—
`9.20.4.14`	affected	—
`9.22.2.20`	affected	—
`9.18.4.71`	affected	—
`9.20.4.19`	affected	—
`9.23.1.26`	affected	—
`9.16.4.89`	affected	—
`9.22.2.32`	affected	—
`9.18.4.76`	affected	—
`9.22.3`	affected	—
`9.24.1.5`	affected	—
`9.20.4.22`	affected	—
`9.24.1.9`	affected	—
`9.20.4.28`	affected	—
`9.16.4.92`	affected	—
`9.18.4.135`	affected	—
`9.23.1.195`	affected	—
`9.20.4.30`	affected	—
`9.24.1.155`	affected	—
`9.23.1.32`	affected	—
`9.18.4.82`	affected	—

Cisco

Cisco Secure Firewall Threat Defense (FTD) Software

unknown

Version	Status	Constraints
`7.0.0`	affected	—
`7.0.0.1`	affected	—
`7.0.1`	affected	—
`7.0.1.1`	affected	—
`7.0.2`	affected	—
`7.2.0`	affected	—
`7.0.2.1`	affected	—
`7.0.3`	affected	—
`7.2.0.1`	affected	—
`7.0.4`	affected	—
`7.2.1`	affected	—
`7.0.5`	affected	—
`7.3.0`	affected	—
`7.2.2`	affected	—
`7.2.3`	affected	—
`7.3.1`	affected	—
`7.2.4`	affected	—
`7.0.6`	affected	—
`7.2.5`	affected	—
`7.2.4.1`	affected	—
`7.3.1.1`	affected	—
`7.4.0`	affected	—
`7.0.6.1`	affected	—
`7.2.5.1`	affected	—
`7.4.1`	affected	—
`7.2.6`	affected	—
`7.0.6.2`	affected	—
`7.4.1.1`	affected	—
`7.2.7`	affected	—
`7.2.5.2`	affected	—
`7.3.1.2`	affected	—
`7.2.8`	affected	—
`7.6.0`	affected	—
`7.4.2`	affected	—
`7.2.8.1`	affected	—
`7.0.6.3`	affected	—
`7.4.2.1`	affected	—
`7.2.9`	affected	—
`7.0.7`	affected	—
`7.7.0`	affected	—
`7.4.2.2`	affected	—
`7.2.10`	affected	—
`7.6.1`	affected	—
`7.4.2.3`	affected	—
`7.0.8`	affected	—
`7.6.2`	affected	—
`7.7.10`	affected	—
`7.7.11`	affected	—
`7.0.8.1`	affected	—
`7.6.2.1`	affected	—
`7.7.10.1`	affected	—
`7.4.2.4`	affected	—
`7.2.10.2`	affected	—
`7.4.3`	affected	—
`7.6.4`	affected	—
`10.0.0`	affected	—
`7.4.4`	affected	—
`7.0.9`	affected	—
`7.2.11`	affected	—
`7.4.7`	affected	—

No data.

Vendor Product Versions

Cisco

Adaptive Security Appliance Software

Version	Status	Scheme	Platform
`[9.16.1,9.16.4.89]`	affected	generic	—
`[9.18.1,9.18.4.135]`	affected	generic	—
`[9.20.1,9.20.4.30]`	affected	generic	—
`[9.23.1,9.23.1.195]`	affected	generic	—
`[9.24.1,9.24.1.155]`	affected	generic	—

Cisco

Secure Firewall Threat Defense

Version	Status	Scheme	Platform
`[7.0.0,7.0.9]`	affected	generic	—
`[7.2.0,7.2.11]`	affected	generic	—
`[7.3.0,7.3.1.2]`	affected	generic	—
`[7.4.0,7.4.7]`	affected	generic	—
`[7.6.0,7.6.4]`	affected	generic	—
`[7.7.0,7.7.11]`	affected	generic	—
`[10.0.0,10.0.0]`	affected	generic	—

Remediation

No solution or workaround provided in the CVE record

Tracking

Advisories

No advisories available

Metrics

No CVSS v4.0

Attack Vector Network

Attack Complexity Low

Privileges Required None

Scope Changed

Confidentiality Impact None

Integrity Impact None

Availability Impact High

User Interaction None

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

Exploit prediction score: < 1% (0.417% probability within 30 days)

Exploitation none

Automatable yes

Technical Impact partial

References

Link	Providers
https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-asaftd-ikev2cert-dos-uWyc2xtv

History

Sep 19, 2026 11:00 PM First appearance in the feed. Affected vendors updated View changes

Type	Values Removed	Values Added
First Time appeared		Cisco Cisco adaptive Security Appliance Software Cisco secure Firewall Threat Defense
Vendors & Products		Cisco Cisco adaptive Security Appliance Software Cisco secure Firewall Threat Defense

Sep 18, 2026 9:30 PM Scoring metrics updated View changes

Type	Values Removed	Values Added
Metrics		ssvc `{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}`

Sep 16, 2026 8:30 PM Description updated. Title updated. Weaknesses updated. Added references. Scoring metrics updated View changes

Type	Values Removed	Values Added
Description		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.
Title		Cisco Secure Firewall Adaptive Security Appliance and Secure Firewall Threat Defense Software IKEv2 Certificate Authentication Denial of Service Vulnerability
Weaknesses		CWE-704
References		https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-asaftd-ikev2cert-dos-uWyc2xtv
Metrics		cvssV3_1 `{'score': 8.6, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H'}`