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.

Classification

CVE ID: CVE-2025-20144

CVSS Base Severity: MEDIUM

CVSS Base Score: 4.0

CVSS Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:L/A:N

Affected Products

Vendor: Cisco

Product: Cisco IOS XR Software

Exploit Prediction Scoring System (EPSS)

EPSS Score: 0.03% (probability of being exploited)

EPSS Percentile: 4.43% (scored less or equal to compared to others)

EPSS Date: 2025-04-10 (when was this score calculated)

References

https://nvd.nist.gov/vuln/detail/CVE-2025-20144
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/

Timeline