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

Cisco Secure Firewall ASA and FTD Software contain a denial of service vulnerability caused by a logic error in the certificate authentication phase of IKEv2, letting unauthenticated remote attackers crash the IKEv2 process via crafted certificates.

CVSS base score 8.6 /10
High
CISA KEV
Not listed
Public exploit
None known
Authentication
Not required
EPSS
0.40% chance of exploitation in 30 days
View the NVD record ↗

Details

Type
Denial of Service
Impact
Denial Of Service
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
Published
16 September 2026
Updated
15 October 2026
Weakness
CWE-704

Vendor fix

Update to the latest available version of Cisco Secure Firewall ASA and FTD Software.

Patching closes this CVE. It does not tell you which of your systems run the affected version, or what else is exposed alongside them.

References

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