CVE-2026-77191 Missing authorization in EOS
An authenticated supplicant can bypass network authorization policies and send unrestricted traffic during a brief timing window in Arista EOS.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-77191?
CVE-2026-77191 is a low-severity missing authorization vulnerability in Arista Networks EOS, published on 14 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
An authenticated supplicant on an adjacent network may bypass intended network authorization policy and send unrestricted traffic during a brief window (milliseconds to seconds) between the completion of the authentication phase and the full enforcement of its assigned ACL.
Weakness: CWE-862
Which versions are affected by CVE-2026-77191?
How do I fix CVE-2026-77191?
No fix has been published for CVE-2026-77191 yet. Limit exposure of the affected software until one is available.
Upgrade, and check permissions on every request on the server, not only in the interface. More about Missing authorization.
Is CVE-2026-77191 being exploited?
There is no known exploitation of CVE-2026-77191 in the wild and no public exploit code.
Sources
Also known as GHSA-x5j2-9m8v-88hr.