CVE-2022-20767: Cisco Firepower Threat Defense Software DNS Enforcement Denial of Service Vulnerability

Severity: high (CVSS 7.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 1.7% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2022-05-03 · updated 2026-08-11
Weakness: CWE-399

Description

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.

Affected products

Cisco Firepower Threat Defense Software: before 7.0.2; 7.1.0 — fixed in 7.0.2

How to fix

Upgrade to a fixed version: Cisco Firepower Threat Defense Software 7.0.2. Check the vendor advisory for mitigations.

References

Get alerted when CVE-2022-20767 or the next vulnerability affects your stack