Cisco IOS XR up to 7.10.1 IPv4 Access Control List denial of service

Summaryinfo

A vulnerability identified as problematic has been detected in Cisco IOS XR. The impacted element is an unknown function of the component IPv4 Access Control List. This manipulation causes denial of service. This vulnerability is handled as CVE-2025-20142. The attack can be initiated remotely. There is not any exploit available. You should upgrade the affected component.

Detailsinfo

A vulnerability was found in Cisco IOS XR. It has been declared as critical. Affected by this vulnerability is some unknown functionality of the component IPv4 Access Control List. The manipulation with an unknown input leads to a denial of service vulnerability. The CWE definition for the vulnerability is CWE-404. The product does not release or incorrectly releases a resource before it is made available for re-use. As an impact it is known to affect availability. The summary by CVE is:

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.

The advisory is shared at sec.cloudapps.cisco.com. This vulnerability is known as CVE-2025-20142 since 10/10/2024. The exploitation appears to be easy. The attack can be launched remotely. The exploitation doesn't need any form of authentication. Neither technical details nor an exploit are publicly available. The price for an exploit might be around USD $0-$5k at the moment (estimation calculated on 08/01/2025). MITRE ATT&CK project uses the attack technique T1499 for this issue.

Upgrading eliminates this vulnerability.

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Productinfo

Type

• Router Operating System

Vendor

• Cisco

Name

• IOS XR

Version

• 6.7.2
• 6.7.3
• 6.7.35
• 6.8.1
• 6.8.2
• 6.9.1
• 6.9.2
• 7.1.2
• 7.1.3
• 7.1.15
• 7.1.25
• 7.3.1
• 7.3.2
• 7.3.3
• 7.3.4
• 7.3.5
• 7.4.1
• 7.4.2
• 7.5.1
• 7.5.2
• 7.5.3
• 7.5.4
• 7.5.5
• 7.6.1
• 7.6.2
• 7.7.1
• 7.7.2
• 7.8.1
• 7.8.2
• 7.8.22
• 7.8.23
• 7.9.1
• 7.9.2
• 7.10.1

License

• commercial

Website

• Vendor: https://www.cisco.com/

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