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VulnerabilityPublished

CVE-2026-121295: Arista Networks EOS · Improper Validation of Specified Quantity in Input

Affects Arista Networks EOSSource CVE Database V5

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Not known to be exploited · CVSS 8.6 High : upgrade to 4.33.0F or 4.32.0F soon.

Data as of 10 Nov 2026, 20:32 UTC

CVSS 3.1 base score
8.6High
How severe the flaw is on the 0–10 CVSS scale.

Thin evidence

One scorer or none
CVSS scores by source
CNA (Arista)CVSS 3.18.6
CNA (Arista)CVSS 4.09.2
Patch
Available – fixed in 4.33.0F, 4.32.0F
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/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 Arista Networks 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

Upgrade affected Arista EOS devices to versions 4.32.0F or 4.33.0F or later, where the vulnerability is fixed. Since this is not a cloud service, remediation requires manual patching. No other mitigations or workarounds are specified.

Description

CVE-2026-121295 is a high-severity vulnerability in Arista Networks EOS affecting versions from 1.0.0 up to 4.36.2F. It involves improper validation of specified quantity in input for S-BFD PDUs, allowing an unauthenticated attacker to send a crafted PDU to an initiator device configured as an S-BFD peer. This can cause the kernel on the initiator device to crash and reboot unexpectedly. Fixed versions include 4.32.0F and 4.33.0F.

References

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