Denial of Service in Cisco Secure Firewall ASA and FTD Software
CVE-2026-20249

8.6HIGH

Key Information:

Vendor

Cisco
Status
Cisco Secure Firewall Adaptive Security Appliance (asa) Software
Cisco Secure Firewall Threat Defense (ftd) Software
Vendor
CVE Published:
16 September 2026

Badges

👾 Exploit Exists

What is CVE-2026-20249?

A vulnerability in the certificate authentication feature of IKEv2 for Cisco Secure Firewall ASA and FTD Software allows an unauthenticated remote attacker to disrupt device operations. This flaw originates from a logic error during the certificate authentication phase of the IKEv2 connection setup. By exploiting this issue with a specially crafted certificate while attempting to establish an IKEv2 VPN connection, an attacker can cause the IKEv2 process to crash, resulting in a denial of service condition. Organizations using affected versions should review their configurations and apply recommended patches.

Affected Version(s)

Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.16.1

Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.16.1.28

Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.16.2

References

https://sec.cloudapps.cisco.com/security/center/content/C...

CVSS V3.1

Score:
8.6
Severity:
HIGH
Confidentiality:
None
Integrity:
None
Availability:
None
Attack Vector:
Network
Attack Complexity:
Low
Privileges Required:
None
User Interaction:
None
Scope:
Changed

Timeline

  • 👾

    Exploit known to exist

  • Vulnerability published

  • Vulnerability Reserved

.