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Cisco IOS XR Software for ASR 9000 Series Routers IPv4 Unicast Packets Denial of Service Vulnerability

cisco-sa-ipv4uni-LfM3cfBu · High · Published · 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-LfM3cfBu This 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.

Cisco advisory ·CSAF JSON

Workarounds

There are no workarounds that addresses this vulnerability. However, removing the configured IPv4 ACL or QoS policy from the affected interface mitigates this vulnerability.

While this mitigation has been deployed and was proven successful in a test environment, customers should determine the applicability and effectiveness in their own environment and under their own use conditions. Customers should be aware that any workaround or mitigation that is implemented may negatively impact the functionality or performance of their network based on intrinsic customer deployment scenarios and limitations. Customers should not deploy any workarounds or mitigations before first evaluating the applicability to their own environment and any impact to such environment.

CVEsCVE-2025-20142
Cisco Bug IDsCSCwf56155
CVSS ScoreBase 8.6
Base 8.6 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H/E:X/RL:X/RC:X
Product Names From Source
Cisco IOS XR Software, Cisco IOS

CSAF Product Statuses

Product Status Source CVE Rows
Cisco IOS XR Software known_affected cisco_csaf CVE-2025-20142 1

Related Products

Product CVE Evidence
Cisco ASR 9000 Series Aggregation Services Routers CVE-2025-20142 Cisco OpenVuln · family-level
Cisco IOS XR Software CVE-2025-20142 Cisco OpenVuln
Cisco IOS CVE-2025-20142 Cisco OpenVuln
Cisco IOS Software CVE-2025-20142 Cisco OpenVuln