---
id: CVE-2024-20434
title: >-
  Cisco Catalyst 9000 Series Switches Denial of Service Vulnerability
  (CVE-2024-20434)
summary: "A vulnerability in Cisco IOS XE Software could allow an unauthenticated, adjacent attacker to cause a denial of service (DoS) condition on the control plane of an affected device.\r\n\r\nThis vulnerability is due to improper handling of frames…"
severity: medium
cvss: 4.3
cvssVector: 'CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L'
cvssSource: vendor
vendor: Cisco
product: Cisco IOS XE Software
affected:
  - ios_xe_software 16.6.1
  - ios_xe_software 16.7.1
  - ios_xe_software 16.8.1
  - ios_xe_software 16.9.1
  - ios_xe_software 16.10.1
  - ios_xe_software 16.11.1
  - ios_xe_software 16.12.1
  - ios_xe_software 16.6.2
  - ios_xe_software 16.6.3
  - ios_xe_software 16.9.2
  - ios_xe_software 16.6.4
  - ios_xe_software 16.8.1a
  - ios_xe_software 16.8.1s
  - ios_xe_software 16.6.5
  - ios_xe_software 16.9.1s
  - ios_xe_software 16.6.4s
  - ios_xe_software 17.1.1
  - ios_xe_software 16.6.4a
  - ios_xe_software 16.9.3
  - ios_xe_software 17.2.1
  - ios_xe_software 16.9.2s
  - ios_xe_software 16.10.1s
  - ios_xe_software 16.6.6
  - ios_xe_software 17.3.1
  - ios_xe_software 16.10.1e
  - ios_xe_software 16.11.1b
  - ios_xe_software 16.6.7
  - ios_xe_software 16.11.1s
  - ios_xe_software 16.9.4
  - ios_xe_software 16.9.3s
  - ios_xe_software 17.4.1
  - ios_xe_software 17.5.1
  - ios_xe_software 17.6.1
  - ios_xe_software 16.11.1c
  - ios_xe_software 16.12.1s
  - ios_xe_software 16.12.1c
  - ios_xe_software 16.12.2
  - ios_xe_software 16.9.5
  - ios_xe_software 16.12.3
  - ios_xe_software 16.12.8
published: '2024-09-25'
updated: '2024-10-04'
sourceUpdated: '2024-10-04T21:53:25+00:00'
source: CSAF
sourceUrl: >-
  https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-vlan-dos-27Pur5RT
references:
  - url: >-
      https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-vlan-dos-27Pur5RT
  - url: 'https://software.cisco.com'
tags:
  - csaf
  - vendor-advisory
  - cisco
epss: 0.00257
epssPercentile: 0.162
ingestedAt: '2026-10-15T11:50:11.865Z'
---

## Overview

A vulnerability in Cisco IOS XE Software could allow an unauthenticated, adjacent attacker to cause a denial of service (DoS) condition on the control plane of an affected device.

This vulnerability is due to improper handling of frames with VLAN tag information. An attacker could exploit this vulnerability by sending crafted frames to an affected device. A successful exploit could allow the attacker to render the control plane of the affected device unresponsive. The device would not be accessible through the console or CLI, and it would not respond to ping requests, SNMP requests, or requests from other control plane protocols. Traffic that is traversing the device through the data plane is not affected. A reload of the device is required to restore control plane services.

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 and IOS XE 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 and IOS XE Software Security Advisory Bundled Publication ["https://sec.cloudapps.cisco.com/security/center/viewErp.x?alertId=ERP-75169"].

## Vendor advisories

- **cisco-sa-vlan-dos-27Pur5RT** · Cisco · affected: Cisco IOS XE Software (97 versions) · updated 2024-10-04 · [advisory](https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-vlan-dos-27Pur5RT)

**Cisco Catalyst 9000 Series Switches Denial of Service Vulnerability**. Released 2024-09-25, updated 2024-10-04.

Affected:

- Cisco IOS XE Software 16.6.1
- Cisco IOS XE Software 16.7.1
- Cisco IOS XE Software 16.8.1
- Cisco IOS XE Software 16.9.1
- Cisco IOS XE Software 16.10.1
- Cisco IOS XE Software 16.11.1
- Cisco IOS XE Software 16.12.1
- Cisco IOS XE Software 16.6.2
- Cisco IOS XE Software 16.6.3
- Cisco IOS XE Software 16.9.2
- Cisco IOS XE Software 16.6.4
- Cisco IOS XE Software 16.8.1a
- Cisco IOS XE Software 16.8.1s
- Cisco IOS XE Software 16.6.5
- Cisco IOS XE Software 16.9.1s
- Cisco IOS XE Software 16.6.4s
- Cisco IOS XE Software 17.1.1
- Cisco IOS XE Software 16.6.4a
- Cisco IOS XE Software 16.9.3
- Cisco IOS XE Software 17.2.1
- Cisco IOS XE Software 16.9.2s
- Cisco IOS XE Software 16.10.1s
- Cisco IOS XE Software 16.6.6
- Cisco IOS XE Software 17.3.1
- Cisco IOS XE Software 16.10.1e
- Cisco IOS XE Software 16.11.1b
- Cisco IOS XE Software 16.6.7
- Cisco IOS XE Software 16.11.1s
- Cisco IOS XE Software 16.9.4
- Cisco IOS XE Software 16.9.3s
- Cisco IOS XE Software 17.4.1
- Cisco IOS XE Software 17.5.1
- Cisco IOS XE Software 17.6.1
- Cisco IOS XE Software 16.11.1c
- Cisco IOS XE Software 16.12.1s
- Cisco IOS XE Software 16.12.1c
- Cisco IOS XE Software 16.12.2
- Cisco IOS XE Software 16.9.5
- Cisco IOS XE Software 16.12.3
- Cisco IOS XE Software 16.12.8

## Remediation

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