Medium [CVE-2026-76445] Multiple Cisco Products Snort 3 Denial of Service Vulnerability

Multiple Cisco products are affected by a vulnerability in the Snort 3 Detection Engine that could allow an unauthenticated, remote attacker to cause the detection engine to unexpectedly restart, resulting in a denial of service (DoS) condition.

The vulnerability is due to a flaw in logic handling when General Packet Radio Service (GPRS) Tunneling Protocol (GTP) extension headers are processed within the codec. An attacker could exploit this vulnerability by sending a crafted, fragmented UDP datagram that contains these headers to the Snort 3 Detection Engine of an affected device.

A successful exploit could allow the attacker to cause the detection engine to enter an infinite loop, resulting in a DoS condition.

Cisco has released software updates that address this vulnerability. There are workarounds that address this vulnerability.

This advisory is part of a group of advisories. For a complete list of the advisories and links to them, see Cisco Advance Notification for Publication of October 21, 2026, Security Advisories.

In addition, for further documentation of improvements and fixes in Open Source Snort 3, see Multiple Cisco Products Snort 3 Security Hardening Release: October 2026.

Affected products named by the advisory: Secure Firewall Threat Defense (FTD) Software; Firepower 2100 Series; Firepower 1000 Series; ASA 5500-X Series Firewalls; and 4 more.