CVE-2026-73435

Adjacent routing disruption via crafted OSPFv2 packets

Published Sep 16, 2026 · Updated Sep 16, 2026

Insufficient OSPFv2 packet authenticity checks in Arista EOS 4.36.1F and earlier allow remote attackers to disrupt routing. EOS insufficiently verifies a crafted OSPFv2 packet despite configured cryptographic authentication, causing neighbor adjacencies to flap and packets to be lost. Exposure requires at least two neighbors on one broadcast interface with OSPFv2 cryptographic authentication, and disruption can propagate across the OSPF domain.

CVSS severity8.2
High
EPSS probability0.16%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Insufficient OSPFv2 packet authenticity checks in Arista EOS 4.36.1F and earlier allow remote attackers to disrupt routing. EOS insufficiently verifies a crafted OSPFv2 packet despite configured cryptographic authentication, causing neighbor adjacencies to flap and packets to be lost. Exposure requires at least two neighbors on one broadcast interface with OSPFv2 cryptographic authentication, and disruption can propagate across the OSPF domain.

The record

CVE
CVE-2026-73435
Published
Sep 16, 2026
Updated
Sep 16, 2026
Vendor
Arista Networks
Product
Arista EOS
Classifications
CWE-345, T1498
Attack vector
adjacent
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 16, 2026CVE publishedPublication date reported by the CVE source.
  2. Sep 16, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=1.0.0 <4.33.0F
  2. Affected versionversion=4.33.0F <=4.33.9M
  3. Affected versionversion=4.34.0F <=4.34.7M
  4. Affected versionversion=4.35.0F <=4.35.5M
  5. Affected versionversion=4.36.0F <=4.36.1F

What conditions does exploitation require?

Attack vectoradjacent
Required privilegesunauthenticated

What is affected?

Arista Networks · Arista EOSversion=1.0.0 <4.33.0F; version=4.33.0F <=4.33.9M; version=4.34.0F <=4.34.7M; version=4.35.0F <=4.35.5M; version=4.36.0F <=4.36.1F

Published CVSS scores

8.2Arista NetworksCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:H
7.0Arista NetworksCVSS:4.0/AV:A/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectoradjacent
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-345Insufficient Verification of Data Authenticity
T1498Network Denial of Service

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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