This vulnerability (CVE-2026-73444) involves an incorrect implementation of the authentication algorithm (CWE-303) in Arista EOS when VRRPv2 IP-AH authentication is configured. An attacker with access to the local layer 2 network segment can bypass VRRP authentication mechanisms and claim the virtual router master role. This role takeover enables the attacker to intercept, modify, or discard network traffic sent to the virtual gateway address, potentially disrupting network availability. The issue affects multiple EOS versions starting from 4.33.0 up to but not including specific fixed versions (4.33.10M, 4.34.8M, 4.35.6M, 4.36.2F). No vendor advisory or patch links are provided, and no known exploits have been reported.

An unauthenticated attacker on the same layer 2 network segment can bypass VRRP authentication and assume control of the virtual router master role. This enables the attacker to intercept, modify, or discard traffic destined for the virtual gateway, potentially causing denial of service or traffic manipulation. There is no confidentiality or integrity impact reported beyond traffic disruption. The CVSS score of 4.7 reflects a medium severity primarily due to the potential for availability impact.

Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. No official patch or workaround information is provided in the available data. Until a fix is available, limiting access to the layer 2 network segment where VRRP runs and disabling VRRPv2 IP-AH authentication if feasible may reduce exposure.