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.
Security Impact Rating: High
CVE: CVE-2025-20142
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