CVE-2026-20329 Cisco Secure Firewall - Denial of Service

Cisco Secure Adaptive Security Appliance Software, Cisco Secure Firewall Threat Defense Software, and Cisco Secure Firewall Management Center Software contain an improper handling of exceptional conditions vulnerability (CWE-703), letting attackers cause potential denial of service or unexpected behavior, exploit requires triggering exceptional conditions.

CVSS base score 9.9 /10
Critical
CISA KEV
Not listed
Public exploit
Proof of concept available
Authentication
Required
EPSS
0.45% 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:L/UI:N/S:C/C:H/I:H/A:H
Published
16 September 2026
Updated
15 October 2026
Weakness
CWE-703

Vendor fix

Update to the latest software hardening release provided by Cisco.

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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