Vulnerability in Cisco Secure Firewall Threat Defense (Ftd) Software

CVE-2026-20290

A vulnerability in SSL/TLS certificate parsing in the Snort 2 Detection Engine of Cisco Secure Firewall Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause the Snort 2 Detection Engine to restart. This vulnerability is due to incomplete validation of the SSL certificate. An attacker could exploit this vulnerability by sending a crafted SSL connection setup request to be parsed by Snort 2. A successful exploit could allow the attacker to cause the Snort 2 Detection Engine to restart unexpectedly, resulting in a denial of service (DoS) condition.

CVSS v3 metric

CVSS v3 base score 5.8 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:L.

Affected products

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-20290?
CVE-2026-20290 is a medium-severity vulnerability in Cisco Secure Firewall Threat Defense (Ftd) Software, classified under Buffer Access with Incorrect Length Value. CVSS score: 5.8/10. Published 2026-09-16.
How severe is CVE-2026-20290?
Medium severity. CVSS v3 base score is 5.8 out of 10.