CVE-2026-73437: Arista Networks Eos

Critical severity, CVSS 9.6. EPSS: 0.2% chance of exploitation in the next 30 days.

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.

Affected products

• Arista Networks Eos: from 4.36.0, up to and including 4.36.1F; from 4.35.0, up to and including 4.35.5M; from 4.34.0, up to and including 4.34.7.1M; from 4.33.0, up to and including 4.33.9M

Published 2026-09-15. Last modified 2026-09-17.