Detections
Analytics

Cisco IOS XR Software for ASR 9000 Series Routers IPv4 Unicast Packets DoS (cisco-sa-asr9k-tUyxcyXN)

high Nessus Plugin ID 371388

Synopsis

The remote device is missing a vendor-supplied security patch

Description

According to its self-reported version, Cisco IOS XR is affected by a vulnerability.

 - 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. (CVE-2026-76505)

Please see the included Cisco BIDs and Cisco Security Advisory for more information.

Solution

Upgrade to the relevant fixed version referenced in Cisco bug ID CSCwn39554

See Also

https://bst.cloudapps.cisco.com/bugsearch/bug/CSCwn39554

http://www.nessus.org/u?2bf44c0d

Plugin Details

Severity: High

ID: 371388

File Name: cisco-sa-asr9k-tUyxcyXN-iosxr.nasl

Version: 1.1

Type: Combined

Family: CISCO

Published: 10/23/2026

Updated: 10/23/2026

Supported Sensors: Nessus

Risk Information

VPR

Risk Factor: Low

Score: 3

Percentile: 23.7

CVSS v2

Risk Factor: High

Base Score: 7.8

Vector: CVSS2#AV:N/AC:L/Au:N/C:N/I:N/A:C

CVSS Score Source: CVE-2026-76505

CVSS v3

Risk Factor: High

Base Score: 7.5

Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Vulnerability Information

CPE: cpe:/o:cisco:ios_xr

Required KB Items: Host/Cisco/IOS-XR/Version, Host/Cisco/IOS-XR/Model

Patch Publication Date: 10/21/2026

Vulnerability Publication Date: 10/21/2026

Reference Information

CVE: CVE-2026-76505

CWE: 20

CISCO-SA: cisco-sa-asr9k-tUyxcyXN

IAVA: 2026-A-1198

CISCO-BUG-ID: CSCwn39554