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CVE-2025-20136

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

Published: Aug 14, 2025Updated: Aug 15, 2025 Sources: CVE List NVD BDUCWE-835

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.

CVSS Vector Breakdown

AV:NAC:LPR:NUI:NS:CC:NI:NA:H
Exploitability
AV:NAttack Vector
Network
AC:LAttack Complexity
Low
PR:NPrivileges Required
None
UI:NUser Interaction
None
Scope
S:CScope
Changed
Impact
C:NConfidentiality
None
I:NIntegrity
None
A:HAvailability
High

Weaknesses

Affected Products

ciscocommercialUSNetworking Infrastructureaka cisco systems, cisco systems inc.
cisco systems inc.commercialUSNetworking Infrastructureaka cisco systems, cisco

Attack Graph

Products CVE Techniques Tactics

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Exploitability

0 exploit sources identified

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View exploit details
Official Patch Available

MITRE ATT&CK

1 technique
Impact
View detailed technique mapping

References

Timeline

Published
Aug 14, 2025
Last Updated
Aug 15, 2025

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