---
id: CVE-2026-20084
title: >-
  A vulnerability in the DHCP snooping feature of Cisco IOS XE Software could
  allow an unauthenticated, remote attacker to cause BOOTP packets to be
  forwarded between VLANs, resulting in a denial of service (DoS) condition
summary: "A vulnerability in the DHCP snooping feature of Cisco IOS XE Software could allow an unauthenticated, remote attacker to cause BOOTP packets to be forwarded between VLANs, resulting in a denial of service (DoS) condition. \r\n\r This vulner…"
severity: high
cvss: 8.6
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H'
cwe:
  - CWE-400
vendor: cisco
product: ios_xe
affected:
  - ios_xe = 16.6.1
  - ios_xe = 16.6.2
  - ios_xe = 16.6.3
  - ios_xe = 16.6.4
  - ios_xe = 16.6.4a
  - ios_xe = 16.6.5
  - ios_xe = 16.6.6
  - ios_xe = 16.6.7
  - ios_xe = 16.6.8
  - ios_xe = 16.6.9
  - ios_xe = 16.6.10
  - ios_xe = 16.7.1
  - ios_xe = 16.8.1
  - ios_xe = 16.8.1a
  - ios_xe = 16.8.1s
  - ios_xe = 16.9.1
  - ios_xe = 16.9.1s
  - ios_xe = 16.9.2
  - ios_xe = 16.9.3
  - ios_xe = 16.9.4
  - ios_xe = 16.9.5
  - ios_xe = 16.9.6
  - ios_xe = 16.9.7
  - ios_xe = 16.9.8
  - ios_xe = 16.10.1
  - ios_xe = 16.10.1e
  - ios_xe = 16.10.1s
  - ios_xe = 16.11.1
  - ios_xe = 16.11.1b
  - ios_xe = 16.11.1s
  - ios_xe = 16.12.1
  - ios_xe = 16.12.1c
  - ios_xe = 16.12.1s
  - ios_xe = 16.12.2
  - ios_xe = 16.12.2s
  - ios_xe = 16.12.3
  - ios_xe = 16.12.3a
  - ios_xe = 16.12.3s
  - ios_xe = 16.12.4
  - ios_xe = 16.12.4a
  - ios_xe = 16.12.5
  - ios_xe = 16.12.5b
  - ios_xe = 16.12.6
  - ios_xe = 16.12.6a
  - ios_xe = 16.12.7
  - ios_xe = 16.12.8
  - ios_xe = 17.1.1
  - ios_xe = 17.1.1s
  - ios_xe = 17.1.1t
  - ios_xe = 17.1.3
  - ios_xe = 17.2.1
  - ios_xe = 17.2.1a
  - ios_xe = 17.3.1
  - ios_xe = 17.3.2
  - ios_xe = 17.3.2a
  - ios_xe = 17.3.3
  - ios_xe = 17.3.4
  - ios_xe = 17.3.5
  - ios_xe = 17.3.6
  - ios_xe = 17.3.7
  - ios_xe = 17.3.8
  - ios_xe = 17.3.8a
  - ios_xe = 17.4.1
  - ios_xe = 17.5.1
  - ios_xe = 17.6.1
  - ios_xe = 17.6.1y
  - ios_xe = 17.6.2
  - ios_xe = 17.6.3
  - ios_xe = 17.6.4
  - ios_xe = 17.6.5
  - ios_xe = 17.6.5a
  - ios_xe = 17.6.6
  - ios_xe = 17.6.6a
  - ios_xe = 17.6.7
  - ios_xe = 17.6.8
  - ios_xe = 17.7.1
  - ios_xe = 17.8.1
  - ios_xe = 17.9.1
  - ios_xe = 17.9.2
  - ios_xe = 17.9.3
  - ios_xe = 17.9.4
  - ios_xe = 17.9.4a
  - ios_xe = 17.9.5
  - ios_xe = 17.9.6
  - ios_xe = 17.9.6a
  - ios_xe = 17.9.7
  - ios_xe = 17.9.8
  - ios_xe = 17.10.1
  - ios_xe = 17.10.1b
  - ios_xe = 17.11.1
  - ios_xe = 17.12.1
  - ios_xe = 17.12.1z5
  - ios_xe = 17.12.2
  - ios_xe = 17.12.3
  - ios_xe = 17.12.4
  - ios_xe = 17.12.5
  - ios_xe = 17.13.1
  - ios_xe = 17.14.1
  - ios_xe = 17.15.1
  - ios_xe = 17.15.2
published: '2026-03-25'
updated: '2026-09-28'
sourceUpdated: '2026-09-28T15:18:38.520'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-20084'
references:
  - url: >-
      https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-bootp-WuBhNBxA
    label: psirt@cisco.com
tags:
  - nvd
epss: 0.00354
epssPercentile: 0.26513
ingestedAt: '2026-09-28T16:15:01.327Z'
---

## Overview

A vulnerability in the DHCP snooping feature of Cisco IOS XE Software could allow an unauthenticated, remote attacker to cause BOOTP packets to be forwarded between VLANs, resulting in a denial of service (DoS) condition. 

 This vulnerability is due to improper handling of BOOTP packets on Cisco Catalyst 9000 Series Switches. An attacker could exploit this vulnerability by sending BOOTP request packets to an affected device. A successful exploit could allow an attacker to forward BOOTP packets from one VLAN to another, resulting in BOOTP VLAN leakage and potentially leading to high CPU utilization. This makes the device unreachable (either through console or remote management) and unable to forward traffic, resulting in a DoS condition. 

 Note: This vulnerability can be exploited with either unicast or broadcast BOOTP packets.

   There are workarounds that address this vulnerability.

## Affected

- `ios_xe = 16.6.1`
- `ios_xe = 16.6.2`
- `ios_xe = 16.6.3`
- `ios_xe = 16.6.4`
- `ios_xe = 16.6.4a`
- `ios_xe = 16.6.5`
- `ios_xe = 16.6.6`
- `ios_xe = 16.6.7`
- `ios_xe = 16.6.8`
- `ios_xe = 16.6.9`
- `ios_xe = 16.6.10`
- `ios_xe = 16.7.1`
- `ios_xe = 16.8.1`
- `ios_xe = 16.8.1a`
- `ios_xe = 16.8.1s`
- `ios_xe = 16.9.1`
- `ios_xe = 16.9.1s`
- `ios_xe = 16.9.2`
- `ios_xe = 16.9.3`
- `ios_xe = 16.9.4`
- `ios_xe = 16.9.5`
- `ios_xe = 16.9.6`
- `ios_xe = 16.9.7`
- `ios_xe = 16.9.8`
- `ios_xe = 16.10.1`
- `ios_xe = 16.10.1e`
- `ios_xe = 16.10.1s`
- `ios_xe = 16.11.1`
- `ios_xe = 16.11.1b`
- `ios_xe = 16.11.1s`
- `ios_xe = 16.12.1`
- `ios_xe = 16.12.1c`
- `ios_xe = 16.12.1s`
- `ios_xe = 16.12.2`
- `ios_xe = 16.12.2s`
- `ios_xe = 16.12.3`
- `ios_xe = 16.12.3a`
- `ios_xe = 16.12.3s`
- `ios_xe = 16.12.4`
- `ios_xe = 16.12.4a`
- `ios_xe = 16.12.5`
- `ios_xe = 16.12.5b`
- `ios_xe = 16.12.6`
- `ios_xe = 16.12.6a`
- `ios_xe = 16.12.7`
- `ios_xe = 16.12.8`
- `ios_xe = 17.1.1`
- `ios_xe = 17.1.1s`
- `ios_xe = 17.1.1t`
- `ios_xe = 17.1.3`
- `ios_xe = 17.2.1`
- `ios_xe = 17.2.1a`
- `ios_xe = 17.3.1`
- `ios_xe = 17.3.2`
- `ios_xe = 17.3.2a`
- `ios_xe = 17.3.3`
- `ios_xe = 17.3.4`
- `ios_xe = 17.3.5`
- `ios_xe = 17.3.6`
- `ios_xe = 17.3.7`
- `ios_xe = 17.3.8`
- `ios_xe = 17.3.8a`
- `ios_xe = 17.4.1`
- `ios_xe = 17.5.1`
- `ios_xe = 17.6.1`
- `ios_xe = 17.6.1y`
- `ios_xe = 17.6.2`
- `ios_xe = 17.6.3`
- `ios_xe = 17.6.4`
- `ios_xe = 17.6.5`
- `ios_xe = 17.6.5a`
- `ios_xe = 17.6.6`
- `ios_xe = 17.6.6a`
- `ios_xe = 17.6.7`
- `ios_xe = 17.6.8`
- `ios_xe = 17.7.1`
- `ios_xe = 17.8.1`
- `ios_xe = 17.9.1`
- `ios_xe = 17.9.2`
- `ios_xe = 17.9.3`
- `ios_xe = 17.9.4`
- `ios_xe = 17.9.4a`
- `ios_xe = 17.9.5`
- `ios_xe = 17.9.6`
- `ios_xe = 17.9.6a`
- `ios_xe = 17.9.7`
- `ios_xe = 17.9.8`
- `ios_xe = 17.10.1`
- `ios_xe = 17.10.1b`
- `ios_xe = 17.11.1`
- `ios_xe = 17.12.1`
- `ios_xe = 17.12.1z5`
- `ios_xe = 17.12.2`
- `ios_xe = 17.12.3`
- `ios_xe = 17.12.4`
- `ios_xe = 17.12.5`
- `ios_xe = 17.13.1`
- `ios_xe = 17.14.1`
- `ios_xe = 17.15.1`
- `ios_xe = 17.15.2`

## Remediation

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