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Cisco Firepower Threat Defense Software DNS Enforcement Denial of Service Vulnerability

A vulnerability in the Snort rule evaluation function of Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device.

The vulnerability is due to improper handling of the DNS reputation enforcement rule. An attacker could exploit this vulnerability by sending crafted UDP packets through an affected device to force a buildup of UDP connections. A successful exploit could allow the attacker to cause traffic that is going through the affected device to be dropped, resulting in a DoS condition. 

Note: This vulnerability only affects Cisco FTD devices that are running Snort 3.

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

This advisory is available at the following link:

This advisory is part of the April 2022 release of the Cisco ASA, FTD, and FMC Security Advisory Bundled publication. For a complete list of the advisories and links to them, see Cisco Event Response: April 2022 Cisco ASA, FMC, and FTD Software Security Advisory Bundled Publication.

Security Impact Rating: High

CVE: CVE-2022-20767

Source:: Cisco Security Advisories