CVE-2023-20270: Cisco Secure Firewall Threat Defense

Medium severity, CVSS 5.8. EPSS: 0.7% chance of exploitation in the next 30 days.

A vulnerability in the interaction between the Server Message Block (SMB) protocol preprocessor and the Snort 3 detection engine for Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to bypass the configured policies or cause a denial of service (DoS) condition on an affected device. This vulnerability is due to improper error-checking when the Snort 3 detection engine is processing SMB traffic. An attacker could exploit this vulnerability by sending a crafted SMB packet stream through an affected device. A successful exploit could allow the attacker to cause the Snort process to reload, resulting in a DoS condition.

Affected products

• Cisco Secure Firewall Threat Defense: version 7.1.0 only; version 7.1.0.1 only; version 7.1.0.2 only; version 7.1.0.3 only; version 7.2.0 only; version 7.2.0.1 only; …

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