Cisco IOS XR Software up to 24.4.1 IPv4 Packet Processing denial of service

Summaryinfo

A vulnerability classified as critical was found in Cisco IOS XR Software. The affected element is an unknown function of the component IPv4 Packet Processing. The manipulation results in denial of service. This vulnerability is cataloged as CVE-2026-76505. The attack may be launched remotely. There is no exploit available. Upgrading the affected component is advised.

Detailsinfo

A vulnerability was found in Cisco IOS XR Software. It has been classified as critical. Affected is an unknown function of the component IPv4 Packet Processing. The manipulation with an unknown input leads to a denial of service vulnerability. CWE is classifying the issue as CWE-404. The product does not release or incorrectly releases a resource before it is made available for re-use. This is going to have an impact on availability. CVE summarizes:

A vulnerability in the IPv4 packet processing functionality of Cisco IOS XR Software that affects Cisco ASR 9000 and 9900 Series Aggregation Services Routers as well as Cisco ASR 9902 and 9903 Compact High-Performance Routers could allow an unauthenticated, remote attacker to cause network processor (NP) errors, resulting in a line card reset or shutdown and a denial of service (DoS) condition.  This vulnerability is due to the incorrect handling of crafted IPv4 packets that are received on an affected line card interface and processed as for-us traffic. The issue can result in an NP reset, causing traffic loss on the affected line card while it recovers. Under repeated reset conditions, the network processor may enter a persistent shutdown state, in which case an explicit line card reload may be required to restore traffic. The vulnerability is within the IPv4 packet-processing path. Transit IPv4 traffic does not trigger this issue and IPv6 traffic cannot trigger it.

The advisory is available at sec.cloudapps.cisco.com. This vulnerability is traded as CVE-2026-76505 since 08/19/2026. The exploitability is told to be easy. It is possible to launch the attack remotely. The exploitation doesn't require any form of authentication. The technical details are unknown and an exploit is not available. The structure of the vulnerability defines a possible price range of USD $0-$5k at the moment (estimation calculated on 10/21/2026). This vulnerability is assigned to T1499 by the MITRE ATT&CK project.

Upgrading eliminates this vulnerability.

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Productinfo

Type

• Router Operating System

Vendor

• Cisco

Name

• IOS XR Software

Version

• 6.7.1
• 6.7.2
• 6.7.3
• 6.7.35
• 6.8.1
• 6.8.2
• 6.9.1
• 6.9.2
• 7.0.1
• 7.0.2
• 7.0.90
• 7.1.1
• 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
• 7.9.21
• 7.10.1
• 7.10.2
• 7.11.1
• 7.11.2
• 7.11.21
• 24.1.1
• 24.1.2
• 24.2.1
• 24.2.2
• 24.3.1
• 24.3.2
• 24.3.20
• 24.3.30
• 24.4.1

License

• commercial

Website

• Vendor: https://www.cisco.com/

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