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VulnerabilityPublished Updated

CVE-2026-73437: Arista Networks EOS · Insufficient Verification of Data Authenticity

Affects Arista Networks EOSSource CVE Database V5

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Not known to be exploited · CVSS 9.6 Critical · fixed in 4.36.2F : patch Arista Networks EOS as a priority.

Data as of 30 Oct 2026, 20:25 UTC

CVSS 3.1 base score
9.6Critical
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.2% chance of exploitation in 30 days – higher than 10% 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:A/AC:L/PR:N/UI:N/S:C/C:H/I:H/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 Arista Networks EOS to 4.36.2F, 4.35.6M, 4.34.8M or 4.33.10M.

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 <4.33.10M
Fixed in
  • 4.33.10M

AI-suggested

If you cannot patch yet, consider restricting network access to DHCP relay agents and monitoring DHCP traffic for anomalies. Avoid relying on DHCP relay configurations that accept replies from untrusted sources.

Description

On affected platforms running Arista EOS with Dynamic Host Configuration Protocol (DHCP) relay configured, an unauthenticated attacker with network access could send a crafted DHCP reply packet from an IP address that is not configured as a helper address, and the relay agent would forward it to clients without validating the source. This could allow the attacker to supply clients with malicious network configuration parameters, potentially resulting in traffic interception or denial of service for affected clients.

References

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