CVE-2023-20031: Cisco Secure Firewall Threat Defense

Medium severity, CVSS 5.4. EPSS: 0.3% chance of exploitation in the next 30 days.

A vulnerability in the SSL/TLS certificate handling of Snort 3 Detection Engine integration with Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause the Snort 3 detection engine to restart. This vulnerability is due to a logic error that occurs when an SSL/TLS certificate that is under load is accessed when it is initiating an SSL connection. Under specific, time-based constraints, an attacker could exploit this vulnerability by sending a high rate of SSL/TLS connection requests to be inspected by the Snort 3 detection engine on an affected device. A successful exploit could allow the attacker to cause the Snort 3 detection engine to reload, resulting in either a bypass or a denial of service (DoS) condition, depending on device configuration. The Snort detection engine will restart automatically. No manual intervention is required.

Affected products

• Cisco Secure Firewall Threat Defense: version 6.7.0 only; version 6.7.0.1 only; version 6.7.0.2 only; version 6.7.0.3 only; version 7.0.0 only; version 7.0.0.1 only; …

Published 2023-11-01. Last modified 2026-08-11.