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UK Cyber Defence
VulnerabilityAwaiting Analysis

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.

MEDIUM 5.8EPSS 0.31%

Does this matter?

Lower severity and a low EPSS score (0.31%). Track it; it rarely justifies an emergency change on its own.

Description

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 3.1
5.8 MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:L
EPSS
0.31% probability · 23th percentile
Public exploits
None in Exploit-DB
CISA KEV
Not listed
Weakness
CWE-805
Source
psirt@cisco.com
EPSS trend
0%3%5%26 October 2026: 0.31%26 October 202626 October 2026

EPSS 0.3% since 26 October 2026; no change recorded yet. Points are recorded when the score first appears and whenever it moves by a percentage point or more.

Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.