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CVE-2026-121368VulnerabilityPublished

On affected platforms running Arista EOS with Bidirectional Forwarding Detection (BFD) configured to use keyed MD5 or

Source GCVE Database

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Authoritative record:CVE-2026-121368· High 8.6

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, 23:17 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 4.08.9
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 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

If you cannot patch yet, consider disabling BFD authentication with keyed MD5 or SHA1 if feasible or restricting network adjacency to trusted devices to reduce exposure.

Description

A vulnerability in Arista EOS platforms with Bidirectional Forwarding Detection (BFD) configured to use keyed MD5 or keyed SHA1 authentication allows an unauthenticated attacker with network adjacency to send a crafted BFD packet that causes the system to reboot. This results in a denial of service condition. The vulnerability has a high severity score of 8.6 and impacts system availability.

References

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