Advisory Published

cisco-sa-ipv4uni-LfM3cfBu: Cisco IOS XR Software for ASR 9000 Series Routers IPv4 Unicast Packets Denial of Service Vulnerability

First published: Wed Mar 12 2025(Updated: )

A vulnerability in the IPv4 access control list (ACL) feature and quality of service (QoS) policy feature of Cisco IOS XR Software for Cisco ASR 9000 Series Aggregation Services Routers, ASR 9902 Compact High-Performance Routers, and ASR 9903 Compact High-Performance Routers could allow an unauthenticated, remote attacker to cause a line card to reset, resulting in a denial of service (DoS) condition.This vulnerability is due to the incorrect handling of malformed IPv4 packets that are received on line cards where the interface has either an IPv4 ACL or QoS policy applied. An attacker could exploit this vulnerability by sending crafted IPv4 packets through an affected device. A successful exploit could allow the attacker to cause network processor errors, resulting in a reset or shutdown of the network process. Traffic over that line card would be lost while the line card reloads.Note: This vulnerability has predominantly been observed in Layer 2 VPN (L2VPN) environments where an IPv4 ACL or QoS policy has been applied to the bridge virtual interface. Layer 3 configurations where the interface has either an IPv4 ACL or QoS policy applied are also affected, though the vulnerability has not been observed.Cisco has released software updates that address this vulnerability. There are no workarounds that address this vulnerability. There are mitigations that address this vulnerability.This advisory is available at the following link:https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ipv4uni-LfM3cfBuThis advisory is part of the March 2025 release of the Cisco IOS XR Software Security Advisory Bundled Publication. For a complete list of the advisories and links to them, see Cisco Event Response: March 2025 Semiannual Cisco IOS XR Software Security Advisory Bundled Publication.

Affected SoftwareAffected VersionHow to fix
Cisco IOS XRv 9000

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Frequently Asked Questions

  • What is the severity of cisco-sa-ipv4uni-LfM3cfBu?

    The severity of cisco-sa-ipv4uni-LfM3cfBu is classified as high.

  • How do I fix cisco-sa-ipv4uni-LfM3cfBu?

    To fix cisco-sa-ipv4uni-LfM3cfBu, update your Cisco IOS XR Software to the latest released version that addresses this vulnerability.

  • What devices are affected by cisco-sa-ipv4uni-LfM3cfBu?

    cisco-sa-ipv4uni-LfM3cfBu affects Cisco ASR 9000 Series Routers, ASR 9902, and ASR 9903 Compact High-Performance Routers.

  • What are the risks of not addressing cisco-sa-ipv4uni-LfM3cfBu?

    Not addressing cisco-sa-ipv4uni-LfM3cfBu could lead to unauthorized access to the network and potential data breaches.

  • Is there a workaround for cisco-sa-ipv4uni-LfM3cfBu?

    Currently, there are no credible workarounds for cisco-sa-ipv4uni-LfM3cfBu, and patching is recommended.

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