Auth bypass in Arista Networks Eos

CVE-2026-77191

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.

Vulnerability class: Broken Access Control

Published · last modified .

CVSS v3 metric

CVSS v3 base score 2.6 (Low). Vector: CVSS:3.1/AV:A/AC:H/PR:L/UI:N/S:U/C:N/I:L/A:N.

EPSS exploit prediction

EPSS: 0.002 (13.0th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 13th percentile — 13.0% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2026-77191: held from 0.002 to 0.002.

EPSS over last 30 days · oldest: 0.002 · newest: 0.002 · change: 0.000

Affected products

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-77191?
CVE-2026-77191 is a low-severity vulnerability in Arista Networks Eos, classified under Missing Authorization. CVSS score: 2.6/10. Published 2026-09-14.
How severe is CVE-2026-77191?
Low severity. CVSS v3 base score is 2.6 out of 10.