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VulnerabilityPublished

CVE-2026-73449: Arista Networks EOS · Authentication Bypass by Spoofing

Affects Arista Networks EOSSource CVE Database V5

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Not known to be exploited · CVSS 5.9 Medium.

Data as of 5 Nov 2026, 23:24 UTC

CVSS 3.1 base score
5.9Medium
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.2% chance of exploitation in 30 days – higher than 15% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CISA SSVC
Exploitation
No evidence of active exploitation and no public proof of concept
Automatable
Attackers cannot reliably automate steps 1–4 of the kill chain
Technical impact
Limited control over the software or limited information exposure

CISA SSVC assessment, 2026-09-15.

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

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 14 Sep 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 5 Nov 2026.

What to do

Affected software

ProductAffectedFixed in
Arista NetworksEOSAffected
  • >=4.36.0 <=4.36.1F
  • >=4.35.0 <=4.35.5M
  • >=4.34.0 <=4.34.7.1M
Fixed in–

AI-suggested

Mitigation requires ensuring that both 802.1X port authentication with dynamic authorization and RADIUS proxy with dynamic authorization are not simultaneously configured unless necessary, or applying any vendor-provided updates once available. Monitor Arista Networks advisories for patches addressing this issue.

Description

CVE-2026-73449 is an authentication bypass vulnerability in Arista Networks EOS affecting configurations with both 802.1X port authentication and RADIUS proxy dynamic authorization enabled. A low-privileged attacker on an adjacent network segment can induce RADIUS packets through a configured RADIUS proxy client to block dynamic authorization messages such as Change-of-Authorization and Disconnect-Requests. This prevents the disconnection of endpoint sessions that the RADIUS server or network access control system has ordered to be terminated, allowing unauthorized continued network access. The vulnerability requires explicit configuration of both features to be exploitable. No known malicious exploitation has been reported.

References

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