CVE-2024-20407: Cisco Secure Firewall Threat Defense

Medium severity, CVSS 5.8. EPSS: 0.4% chance of exploitation in the next 30 days.

A vulnerability in the interaction between the TCP Intercept feature and the Snort 3 detection engine on Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to bypass configured policies on an affected system. Devices that are configured with Snort 2 are not affected by this vulnerability. This vulnerability is due to a logic error when handling embryonic (half-open) TCP connections. An attacker could exploit this vulnerability by sending a crafted traffic pattern through an affected device. A successful exploit could allow unintended traffic to enter the network protected by the affected device.

Affected products

• Cisco Secure Firewall Threat Defense: version 6.2.3 only; version 6.2.3.1 only; version 6.2.3.2 only; version 6.2.3.3 only; version 6.2.3.4 only; version 6.2.3.5 only; …

Published 2024-10-23. Last modified 2026-08-11.