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CVE-2026-77191· NVD / CVE Program· CNA Arista

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

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.

LowCVSS 2.1 · v4.0—No exploit No fix recorded

Noroxi analysis

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Published
Sep 14, 2026
Updated
Sep 16, 2026
EPSS
0.2% · 12th percentile
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Report tools

JSON

Action score

8

Monitor

Low priority for now.

CVSS
8 / 40 · 2.1 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.2%

CISA SSVC decision

Exploitation
none
Automatable
no
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
—
CNA · Arista
2.6
NVD has not scored this yet; the score shown is the CNA’s.

CVSS:3.1/AV:A/AC:H/PR:L/UI:N/S:U/C:N/I:L/A:N

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Affected systems

—

Versions reported by the vendor

Affected version ranges reported by the assigning authority (Arista). Independent of NVD's CPE analysis and usually ahead of it.

  • Arista Networks EOS

    • 4.35.0 and later · up to and including 4.35.0.3Faffected
    • 4.34.0 and later · up to and including 4.34.5Maffected
    • 0.0.0 and later · up to and including 4.33.7.1Maffected

Other highest-scoring records for the same primary product.

  • CVE-2026-73453Security Advisory 0174
    38Monitor
  • CVE-2026-73461Security Advisory 0163
    37Monitor
  • CVE-2026-73447Security Advisory 0162 - gNSI Certz/Bootz OS Command Injection via Crafted Rotate Request
    37Monitor
  • CVE-2026-73456Under certain circumstances, an unauthenticated gNPSI client can craft a malicious request to allow arbitrary code execution, granting an attacker full administ
    36Monitor
  • CVE-2026-73458On affected platforms running Arista EOS with authenticated Bidirectional Forwarding Detection (BFD) sessions configured, a specially crafted packet can cause t
    36Monitor
  • CVE-2025-1260On affected platforms running Arista EOS with OpenConfig configured, a gNOI request can be run when it should have been rejected.
    36Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

No fix version is recorded for this entry. Check the references for vendor advisories.

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

  • Someone on the same network segment can trigger it.
  • A low-privileged account is enough.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
Integrity
Availability
Attack vector
Adjacent
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
X

CVSS vector

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

nvd-secondary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

Change log

No changes recorded on tracked fields yet. Score, KEV, exploit maturity and fix status changes appear here.

References

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records