All of the CVEs covered in this advisory apply to affected platforms running Arista EOS with 802.1X authentication and authorization enabled and Access Control Lists (ACLs) configured for per-supplicant policy enforcement. An authenticated supplicant on an
Summary
| CVE | CVE-2026-77191 |
|---|---|
| State | PUBLISHED |
| Assigner | Arista |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2026-09-14 23:18:36 UTC |
| Updated | 2026-09-16 20:36:52 UTC |
| 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. |
Risk And Classification
Primary CVSS: v4.0 2.1 LOW from [email protected]
CVSS:4.0/AV:A/AC:L/AT:P/PR:L/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
EPSS: 0.001400000 probability, percentile 0.037300000 (date 2026-09-16)
Problem Types: CWE-862 | CWE-862 CWE-862 Missing Authorization
| Version | Source | Type | Score | Severity | Vector |
|---|---|---|---|---|---|
| 4.0 | [email protected] | Secondary | 2.1 | LOW | CVSS:4.0/AV:A/AC:L/AT:P/PR:L/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/C... |
| 4.0 | CNA | CVSS | 2.1 | LOW | CVSS:4.0/AV:A/AC:L/AT:P/PR:L/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N |
| 3.1 | [email protected] | Secondary | 2.6 | LOW | CVSS:3.1/AV:A/AC:H/PR:L/UI:N/S:U/C:N/I:L/A:N |
| 3.1 | CNA | CVSS | 2.6 | LOW | CVSS:3.1/AV:A/AC:H/PR:L/UI:N/S:U/C:N/I:L/A:N |
CVSS v4.0 Breakdown
CVSS:4.0/AV:A/AC:L/AT:P/PR:L/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
CVSS v3.1 Breakdown
CVSS:3.1/AV:A/AC:H/PR:L/UI:N/S:U/C:N/I:L/A:N
Vendor Declared Affected Products
| Source | Vendor | Product | Version | Platforms |
|---|---|---|---|---|
| CNA | Arista Networks | EOS | affected 4.35.0 4.35.0.3F custom | Not specified |
| CNA | Arista Networks | EOS | affected 4.34.0 4.34.5M custom | Not specified |
| CNA | Arista Networks | EOS | affected 0.0.0 4.33.7.1M custom | Not specified |
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| www.arista.com/en/support/advisories-notices/security-advisory/24706-securit... | [email protected] | www.arista.com | |
| CVE Program record | CVE.ORG | www.cve.org | canonical |
| NVD vulnerability detail | NVD | nvd.nist.gov | canonical, analysis |
Vendor Comments And Credit
Discovery Credit
CNA: Those issues were discovered internally by Arista, and the company is not aware of any malicious exploitation of these vulnerabilities in customer networks. (en)
Additional Advisory Data
Solutions
CNA: CVE-2026-77191 has been fixed in the following releases: * 4.35.1F and later releases in the 4.35.x train. * 4.34.6M and later releases in the 4.34.x train. * 4.33.8M and later releases in the 4.33.x train.
Workarounds
CNA: There is no workaround available for CVE-2026-77191.