---
id: CVE-2026-76505
title: >-
  Cisco IOS XR Software for ASR 9000 Series Routers IPv4 Unicast Packets Denial
  of Service Vulnerability
summary: >-
  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…
severity: high
cvss: 7.5
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'
cvssSource: cna
cwe:
  - CWE-20
vendor: Cisco
product: Cisco IOS XR Software
affected:
  - ios_xr_software 7.0.1
  - ios_xr_software 7.1.1
  - ios_xr_software 7.0.90
  - ios_xr_software 6.7.1
  - ios_xr_software 7.0.2
  - ios_xr_software 7.1.15
  - ios_xr_software 7.1.2
  - ios_xr_software 6.7.2
  - ios_xr_software 7.1.25
  - ios_xr_software 7.1.3
  - ios_xr_software 6.7.3
  - ios_xr_software 7.3.1
  - ios_xr_software 7.4.1
  - ios_xr_software 6.8.1
  - ios_xr_software 7.3.2
  - ios_xr_software 7.5.1
  - ios_xr_software 7.6.1
  - ios_xr_software 7.5.2
  - ios_xr_software 7.3.3
  - ios_xr_software 6.8.2
  - ios_xr_software 7.7.1
  - ios_xr_software 7.4.2
  - ios_xr_software 7.3.4
  - ios_xr_software 6.7.35
  - ios_xr_software 6.9.1
  - ios_xr_software 7.6.2
  - ios_xr_software 7.8.1
  - ios_xr_software 7.5.3
  - ios_xr_software 7.7.2
  - ios_xr_software 6.9.2
  - ios_xr_software 7.9.1
  - ios_xr_software 7.8.2
  - ios_xr_software 7.5.4
  - ios_xr_software 7.8.22
  - ios_xr_software 7.10.1
  - ios_xr_software 7.9.2
  - ios_xr_software 7.3.5
  - ios_xr_software 7.5.5
  - ios_xr_software 7.11.1
  - ios_xr_software 7.9.21
  - ios_xr_software 7.10.2
  - ios_xr_software 24.1.1
  - ios_xr_software 7.11.2
  - ios_xr_software 24.2.1
  - ios_xr_software 24.1.2
  - ios_xr_software 24.3.1
  - ios_xr_software 24.4.1
  - ios_xr_software 24.2.2
  - ios_xr_software 7.8.23
  - ios_xr_software 7.11.21
published: '2026-10-21'
updated: '2026-10-21'
sourceUpdated: '2026-10-21T16:18:12.195Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-76505'
references:
  - url: >-
      https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-asr9k-tUyxcyXN
    label: cisco-sa-asr9k-tUyxcyXN
tags:
  - cve.org
ingestedAt: '2026-10-21T17:07:51.298Z'
---

## Overview

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.

## Affected

- `ios_xr_software 7.0.1`
- `ios_xr_software 7.1.1`
- `ios_xr_software 7.0.90`
- `ios_xr_software 6.7.1`
- `ios_xr_software 7.0.2`
- `ios_xr_software 7.1.15`
- `ios_xr_software 7.1.2`
- `ios_xr_software 6.7.2`
- `ios_xr_software 7.1.25`
- `ios_xr_software 7.1.3`
- `ios_xr_software 6.7.3`
- `ios_xr_software 7.3.1`
- `ios_xr_software 7.4.1`
- `ios_xr_software 6.8.1`
- `ios_xr_software 7.3.2`
- `ios_xr_software 7.5.1`
- `ios_xr_software 7.6.1`
- `ios_xr_software 7.5.2`
- `ios_xr_software 7.3.3`
- `ios_xr_software 6.8.2`
- `ios_xr_software 7.7.1`
- `ios_xr_software 7.4.2`
- `ios_xr_software 7.3.4`
- `ios_xr_software 6.7.35`
- `ios_xr_software 6.9.1`
- `ios_xr_software 7.6.2`
- `ios_xr_software 7.8.1`
- `ios_xr_software 7.5.3`
- `ios_xr_software 7.7.2`
- `ios_xr_software 6.9.2`
- `ios_xr_software 7.9.1`
- `ios_xr_software 7.8.2`
- `ios_xr_software 7.5.4`
- `ios_xr_software 7.8.22`
- `ios_xr_software 7.10.1`
- `ios_xr_software 7.9.2`
- `ios_xr_software 7.3.5`
- `ios_xr_software 7.5.5`
- `ios_xr_software 7.11.1`
- `ios_xr_software 7.9.21`
- `ios_xr_software 7.10.2`
- `ios_xr_software 24.1.1`
- `ios_xr_software 7.11.2`
- `ios_xr_software 24.2.1`
- `ios_xr_software 24.1.2`
- `ios_xr_software 24.3.1`
- `ios_xr_software 24.4.1`
- `ios_xr_software 24.2.2`
- `ios_xr_software 7.8.23`
- `ios_xr_software 7.11.21`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.