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VulnerabilityPublished

CVE-2026-73458: Arista Networks EOS · Incorrect Implementation of Authentication Algorithm

Affects Arista Networks EOSSource CVE Database V5

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Not known to be exploited · CVSS 8.2 High · fixed in 4.36.2F : patch Arista Networks EOS soon.

Data as of 30 Oct 2026, 20:25 UTC

CVSS 3.1 base score
8.2High
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.4% chance of exploitation in 30 days – higher than 34% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 4.36.2F, 4.35.6M, 4.34.8M +1
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 15 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 30 Oct 2026.

What to do

Upgrade EOS and arista/eos to 4.36.2F, 4.35.6M, 4.34.8M or 4.33.9M.

Affected software

ProductAffectedFixed in
Arista NetworksEOSAffected
  • >=4.36.0 <4.36.2F
Fixed in
  • 4.36.2F
Arista NetworksEOSAffected
  • >=4.35.0 <4.35.6M
Fixed in
  • 4.35.6M
Arista NetworksEOSAffected
  • >=4.34.0 <4.34.8M
Fixed in
  • 4.34.8M
Arista NetworksEOSAffected
  • >=4.33.0 <4.33.9M
Fixed in
  • 4.33.9M
Aristaarista/eospkg:rpm/arista/eosOther threatsAffected
  • >=4.33.0 <4.33.9M
  • >=4.34.0 <4.34.8M
  • >=4.35.0 <4.35.6M
  • >=4.36.0 <4.36.2F
Fixed in
  • 4.33.9M
  • 4.34.8M
  • 4.35.6M
  • 4.36.2F

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

If you cannot patch yet, consider disabling authenticated BFD sessions if feasible or monitoring BFD session stability. Follow Arista Networks' official advisories for updates and fixes.

Description

On affected platforms running Arista EOS with authenticated Bidirectional Forwarding Detection (BFD) sessions configured, a specially crafted packet can cause the BFD session(s) to go down. This may result in undesirable network changes because various routing protocols monitor status on BFD session(s).

References

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