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CVE-2026-121290VulnerabilityPublished

On affected platforms running Arista EOS with Border Gateway Protocol (BGP) changing the BGP listen port from its

Source GCVE Database

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Authoritative record:CVE-2026-121290· High 8.2

Not known to be exploited · CVSS 8.2 High : upgrade to 4.33.0F or 4.32.0F soon.

Data as of 10 Nov 2026, 23:19 UTC

CVSS 3.1 base score
8.2High
How severe the flaw is on the 0–10 CVSS scale.

Thin evidence

One scorer or none
CVSS scores by source
CNA (Arista)CVSS 3.18.2
CNA (Arista)CVSS 4.08.3
Patch
Available – fixed in 4.33.0F, 4.32.0F
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 10 Nov 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 10 Nov 2026.

What to do

Upgrade EOS to 4.33.0F or 4.32.0F.

Affected software

ProductAffectedFixed in
Arista NetworksEOSAffected
  • >=4.36.0F <=4.36.2F
  • >=4.35.0F <=4.35.6M
  • >=4.34.0F <=4.34.8M
  • >=4.33.0F <=4.33.10M
  • >=4.32.0F <4.33.0F
  • >=1.0.0 <4.32.0F
Fixed in
  • 4.33.0F
  • 4.32.0F

AI-suggested

Users should avoid changing the BGP listen port from its default value unless they implement equivalent ACL protections manually to prevent unauthorized BGP peering. Monitor vendor advisories for any forthcoming patches or official guidance.

Description

On Arista EOS platforms running Border Gateway Protocol (BGP), changing the BGP listen port from its default disables the default protective Access Control List (ACL) rules that guard against unexpected BGP peering attempts. This configuration change can lead to unauthorized or unexpected BGP connections.

References

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