CVE-2026-73438: Security Advisory 0172

Published Sep 16, 2026

Updated

On affected platforms running Arista EOS with Open Shortest Path First version 3 (OSPFv3) configured, an unauthenticated attacker on the same OSPFv3 broadcast domain can send a specially crafted set of packets that can cause the Ospf3 agent to restart unexpectedly. The crash results in the loss of all OSPFv3 adjacencies on the affected device and may disrupt routing across the broader OSPF domain until the agent recovers.

This issue was reported externally by Dravanet Inc., and Arista is not aware of any malicious exploitation of this vulnerability in customer networks.

Affected Software

1 affected component

Arista Arista EOS=3 (OSPFv3)

Remediation

Recommended actions to resolve this vulnerability, in priority order.

Upgrade
Upgrade Arista EOS to a version that resolves this vulnerability.
Fixed in 4.33.10M
Upgrade
Upgrade Arista EOS to a version that resolves this vulnerability.
Fixed in 4.34.8M
Upgrade
Upgrade Arista EOS to a version that resolves this vulnerability.
Fixed in 4.35.6M
Upgrade
Upgrade Arista EOS to a version that resolves this vulnerability.
Fixed in 4.36.2F
Compensating control
If immediate upgrade is not possible, limit exposure of the OSPFv3 broadcast domain by restricting which hosts/networks can participate on the segment (since an unauthenticated attacker on the same OSPFv3 broadcast domain can trigger the Ospf3 agent restart).

Event History

Sep 16, 2026

CVE Published

via MITRE·09:38 AM

Data Sourced

via MITRE·09:38 AM

RemedyDescriptionSeverityWeakness

Frequently Asked Questions

Which devices are exposed to this issue?

Affected platforms are those running Arista EOS with OSPFv3 configured. Exploitation requires the attacker to be on the same OSPFv3 broadcast domain as the target.

What access does an attacker need?

The attacker does not need authentication or user interaction, but must be able to send specially crafted packets from the same OSPFv3 broadcast domain. The attack complexity is rated high.

What is the operational impact of a successful attack?

A successful attack can cause the Ospf3 agent to restart unexpectedly, dropping all OSPFv3 adjacencies on the affected device. Routing disruption can extend across the wider OSPF domain until the agent recovers.

Is there evidence of active exploitation?

Arista states that it is not aware of malicious exploitation in customer networks.