Cisco Secure Firewall Threat Defense Software Snort 3 Denial of Service Vulnerability (CVE-2025-20217)

CVE number = CVE-2025-20217

A vulnerability in the packet inspection functionality of the Snort 3 Detection Engine of Cisco Secure Firewall Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device.

This vulnerability is due to incorrect processing of traffic that is inspected by an affected device. An attacker could exploit this vulnerability by sending crafted traffic through the affected device. A successful exploit could allow the attacker to cause the affected device to enter an infinite loop while inspecting traffic, resulting in a DoS condition. The system watchdog will restart the Snort process automatically.

Cisco has released software updates that address this vulnerability. There are no workarounds that address this vulnerability.

This vulnerability affects Cisco devices if they are running a vulnerable release of Cisco Secure FTD Software and have an intrusion policy enabled that has the Snort 3 engine running.

This advisory is available at the following link:
https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ftd-dos-SvKhtjgt