---
id: CVE-2026-73437
title: >-
  On affected platforms running Arista EOS with Dynamic Host Configuration
  Protocol (DHCP) relay configured, an unauthenticated attacker with network
  access could send a crafted DHCP reply packet from an IP address that is not
  configured a…
summary: >-
  On affected platforms running Arista EOS with Dynamic Host Configuration
  Protocol (DHCP) relay configured, an unauthenticated attacker with network
  access could send a crafted DHCP reply packet from an IP address that is not
  configured a…
severity: critical
cvss: 9.6
cvssVector: 'CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H'
cwe:
  - CWE-345
vendor: Arista Networks
product: EOS
affected:
  - EOS >= 4.36.0 <= 4.36.1F
  - EOS >= 4.35.0 <= 4.35.5M
  - EOS >= 4.34.0 <= 4.34.7.1M
  - EOS >= 4.33.0 <= 4.33.9M
published: '2026-09-15'
updated: '2026-09-17'
sourceUpdated: '2026-09-17T04:17:57.743'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-73437'
references:
  - url: >-
      https://www.arista.com/en/support/advisories-notices/security-advisory/24712-security-advisory-0156
    label: psirt@arista.com
tags:
  - nvd
  - cve.org
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: total
  timestamp: '2026-09-16T19:11:26.919591Z'
epss: 0.00207
epssPercentile: 0.09555
ingestedAt: '2026-09-15T21:44:50.659Z'
---

## Overview

On affected platforms running Arista EOS with Dynamic Host Configuration Protocol (DHCP) relay configured, an unauthenticated attacker with network access could send a crafted DHCP reply packet from an IP address that is not configured as a helper address, and the relay agent would forward it to clients without validating the source. This could allow the attacker to supply clients with malicious network configuration parameters, potentially resulting in traffic interception or denial of service for affected clients.

## Remediation

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