CVE-2025-20136

Cisco Adaptive Security Appliance and Firepower Threat Defense Software Network Address Translation DNS Inspection Denial of Service Vulnerability

State: Published
Severity: 8.6 High
Published: Aug 14, 2025
Updated: Aug 14, 2025
Reserved: Oct 10, 2024

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Description

A vulnerability in the function that performs IPv4 and IPv6 Network Address Translation (NAT) DNS inspection for Cisco Secure Firewall Adaptive Security Appliance (ASA) Software and Cisco Secure Firewall Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause the device to reload unexpectedly, resulting in a denial of service (DoS) condition. 

This vulnerability is due to an infinite loop condition that occurs when a Cisco Secure ASA or Cisco Secure FTD device processes DNS packets with DNS inspection enabled and the device is configured for NAT44, NAT64, or NAT46. An attacker could exploit this vulnerability by sending crafted DNS packets that match a static NAT rule with DNS inspection enabled through an affected device. A successful exploit could allow the attacker to create an infinite loop and cause the device to reload, resulting in a DoS condition.

Scores

CVSS	Score	Vector	Source
3.1	8.6 High	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H	cisco

Weaknesses

CWE-835 Loop with Unreachable Exit Condition ('Infinite Loop')

Affected Products

Product	Versions
Cisco Adaptive Security Appliance (ASA) SoftwareCisco	9.12.3Affected 9.8.3Affected 9.12.1Affected 9.8.1Affected 9.12.2Affected 9.8.2.45Affected 9.8.2Affected 9.8.4Affected 9.14.1Affected 9.12.4Affected 9.8.2.26Affected 9.8.2.24Affected 9.8.2.15Affected 9.8.2.14Affected 9.8.2.35Affected 9.8.2.20Affected 9.8.2.8Affected 9.8.2.17Affected 9.8.2.28Affected 9.8.2.33Affected 9.8.2.38Affected 9.8.4.25Affected 9.12.3.2Affected 9.12.3.7Affected 9.8.3.18Affected and 184 more versions
Cisco Firepower Threat Defense SoftwareCisco	6.2.3.14Affected 6.4.0.1Affected 6.2.3.7Affected 6.2.3Affected 6.4.0.2Affected 6.2.3.9Affected 6.2.3.1Affected 6.2.3.2Affected 6.4.0.5Affected 6.2.3.10Affected 6.4.0Affected 6.4.0.3Affected 6.2.3.6Affected 6.4.0.4Affected 6.2.3.15Affected 6.2.3.5Affected 6.2.3.4Affected 6.2.3.3Affected 6.2.3.8Affected 6.4.0.6Affected 6.2.3.11Affected 6.2.3.12Affected 6.2.3.13Affected 6.4.0.7Affected 6.4.0.8Affected and 66 more versions

Product

Versions

Cisco Adaptive Security Appliance (ASA) SoftwareCisco

9.12.3Affected
9.8.3Affected
9.12.1Affected
9.8.1Affected
9.12.2Affected
9.8.2.45Affected
9.8.2Affected
9.8.4Affected
9.14.1Affected
9.12.4Affected
9.8.2.26Affected
9.8.2.24Affected
9.8.2.15Affected
9.8.2.14Affected
9.8.2.35Affected
9.8.2.20Affected
9.8.2.8Affected
9.8.2.17Affected
9.8.2.28Affected
9.8.2.33Affected
9.8.2.38Affected
9.8.4.25Affected
9.12.3.2Affected
9.12.3.7Affected
9.8.3.18Affected
and 184 more versions

Cisco Firepower Threat Defense SoftwareCisco

6.2.3.14Affected
6.4.0.1Affected
6.2.3.7Affected
6.2.3Affected
6.4.0.2Affected
6.2.3.9Affected
6.2.3.1Affected
6.2.3.2Affected
6.4.0.5Affected
6.2.3.10Affected
6.4.0Affected
6.4.0.3Affected
6.2.3.6Affected
6.4.0.4Affected
6.2.3.15Affected
6.2.3.5Affected
6.2.3.4Affected
6.2.3.3Affected
6.2.3.8Affected
6.4.0.6Affected
6.2.3.11Affected
6.2.3.12Affected
6.2.3.13Affected
6.4.0.7Affected
6.4.0.8Affected
and 66 more versions

References

cisco-sa-asaftd-nat-dns-dos-bqhynHTM

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