CVE-2022-20760: Cisco Adaptive Security Appliance Software and Firepower Threat Defense Software DNS Inspection Denial of Service Vulnerability

Severity: high (CVSS 7.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 1.6% 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-400

Description

A vulnerability in the DNS inspection handler of Cisco Adaptive Security Appliance (ASA) Software and Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause a denial of service condition (DoS) on an affected device. This vulnerability is due to a lack of proper processing of incoming requests. An attacker could exploit this vulnerability by sending crafted DNS requests at a high rate to an affected device. A successful exploit could allow the attacker to cause the device to stop responding, resulting in a DoS condition.

Affected products

Cisco ASA Software: before 9.12.4.38; from 9.13.0 before 9.14.4; from 9.15.0 before 9.15.1.21; from 9.16.0 before 9.16.2.14; from 9.17.0 before 9.17.1.7 — fixed in 9.12.4.38, 9.14.4, 9.15.1.21, 9.16.2.14, 9.17.1.7
Cisco Firepower Threat Defense Software: before 6.4.0.15; from 6.5.0 before 6.6.5.2; from 7.0.0 before 7.0.2; 7.1.0 — fixed in 6.4.0.15, 6.6.5.2, 7.0.2

How to fix

Upgrade to a fixed version: Cisco ASA Software 9.12.4.38, 9.14.4, 9.15.1.21, 9.16.2.14; Cisco Firepower Threat Defense Software 6.4.0.15, 6.6.5.2, 7.0.2. Check the vendor advisory for mitigations.

References

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