CVE-2026-73444

Received Received - Intake

VRRPv2 IP-AH Authentication Bypass in Arista EOS

Publication date: 2026-09-15

Last updated on: 2026-09-15

Assigner: Arista Networks, Inc.

Description

On affected platforms running Arista EOS with VRRPv2 IP Authentication Header (IP-AH) authentication configured, an unauthenticated attacker with access to the layer 2 network segment on which VRRP is running could bypass VRRP authentication and claim the virtual router master role, enabling the attacker to intercept, modify, or discard traffic that hosts on the segment send to the virtual gateway address.

CVSS Scores

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Meta Information

Published

2026-09-15

Last Modified

2026-09-15

Generated

2026-10-06

AI Q&A

2026-09-16

EPSS Evaluated

2026-10-04

NVD

CVE-2026-73444

EUVD

EUVD-2026-80009

Affected Vendors & Products

Vendor	Product	Version / Range
arista	eos	*

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-303	The requirements for the product dictate the use of an established authentication algorithm, but the implementation of the algorithm is incorrect.

Attack-Flow Graph

Executive Summary

This vulnerability affects Arista EOS devices running VRRPv2 with IP Authentication Header (IP-AH) authentication enabled. An unauthenticated attacker on the same layer 2 network segment can bypass VRRP authentication and take over the virtual router master role. This allows the attacker to intercept, modify, or discard traffic sent to the virtual gateway address.

Detection Guidance

Detecting this vulnerability requires checking if VRRPv2 IP Authentication Header (IP-AH) authentication is misconfigured on Arista EOS devices. Inspect VRRP configurations for missing or weak authentication settings. Use commands like 'show running-config | include vrrp' to review VRRP configurations and verify if IP-AH authentication is properly enabled.

Impact Analysis

If exploited, this vulnerability could allow an attacker to gain control of network traffic routing. This may lead to data interception, modification, or loss for devices relying on the virtual gateway. Network integrity and confidentiality could be compromised, affecting operations dependent on stable routing.

Compliance Impact

This vulnerability could lead to unauthorized access or data breaches, which may violate compliance requirements under GDPR (data protection) or HIPAA (health information security). Organizations must ensure network integrity to meet these standards, and exploitation could result in regulatory penalties or loss of certification.

Mitigation Strategies

Immediately disable VRRPv2 IP Authentication Header (IP-AH) authentication if configured, as it is vulnerable. Upgrade Arista EOS to a patched version that addresses this issue. Ensure VRRP is configured with stronger authentication methods like plaintext or message digest authentication (MD5). Restrict layer 2 network access to trusted devices only.

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