CVE-2026-73437

Critical

Description

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.

SeverityCritical

CVSS9.6

Exploit probability—

ProductEOS

PublishedSep 15, 2026

First seenSep 15, 2026

Weakness typeCWE-345CWE-345

How to fix

Vendor advisories

arista.com/en/support/advisories-notices/security-advisory/24712-security-advisory-0156

Affected products

Product	Affected versions	Fixed in
Arista Networks EOS	4.36.0 ≤ v ≤ 4.36.1F, 4.35.0 ≤ v ≤ 4.35.5M, 4.34.0 ≤ v ≤ 4.34.7.1M, 4.33.0 ≤ v ≤ 4.33.9M	—

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