---
id: CVE-2024-20317
title: Cisco IOS XR Software Layer 2 Services Denial of Service Vulnerability
summary: >-
  A vulnerability in the handling of specific Ethernet frames by Cisco IOS XR
  Software for various Cisco Network Convergence System (NCS) platforms could
  allow an unauthenticated, adjacent attacker to cause critical priority packets
  to be dr…
severity: high
cvss: 7.4
cvssVector: 'CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H'
cvssSource: vendor
vendor: Cisco
product: Cisco IOS XR Software
affected:
  - ios_xr_software
published: '2024-09-11'
updated: '2024-09-11'
sourceUpdated: '2024-09-11T16:00:00+00:00'
source: CSAF
sourceUrl: >-
  https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-l2services-2mvHdNuC
references:
  - url: >-
      https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-l2services-2mvHdNuC
  - url: 'https://software.cisco.com'
tags:
  - csaf
  - vendor-advisory
  - cisco
epss: 0.00238
epssPercentile: 0.1327
ingestedAt: '2026-09-19T16:43:01.805Z'
---

## Overview

A vulnerability in the handling of specific Ethernet frames by Cisco IOS XR Software for various Cisco Network Convergence System (NCS) platforms could allow an unauthenticated, adjacent attacker to cause critical priority packets to be dropped, resulting in a denial of service (DoS) condition.

This vulnerability is due to incorrect classification of certain types of Ethernet frames that are received on an interface. An attacker could exploit this vulnerability by sending specific types of Ethernet frames to or through the affected device. A successful exploit could allow the attacker to cause control plane protocol relationships to fail, resulting in a DoS condition. For more information, see the Details ["#details"] section of this advisory.

Cisco has released software updates that address this vulnerability. There are no workarounds that address this vulnerability.



This advisory is part of the September 2024 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: September 2024 Semiannual Cisco IOS XR Software Security Advisory Bundled Publication ["https://sec.cloudapps.cisco.com/security/center/viewErp.x?alertId=ERP-75416"].

## Vendor advisories

- **cisco-sa-l2services-2mvHdNuC** · Cisco · affected: Cisco IOS XR Software · updated 2024-09-11 · [advisory](https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-l2services-2mvHdNuC)

**Cisco IOS XR Software Network Convergence System Denial of Service Vulnerability**. Released 2024-09-11.

Affected:

- Cisco IOS XR Software

## Remediation

Cisco has released software updates that address this vulnerability. https://software.cisco.com