CVE-2026-73438

Routing interruption via reachable Ospf3 assertion

Published Sep 16, 2026 · Updated Sep 16, 2026

Reachable assertion in the Ospf3 agent in Arista EOS allows remote attackers to interrupt OSPFv3 routing with crafted packets. The agent accepts a specially crafted packet sequence from its broadcast domain and reaches an assertion that restarts the process. OSPFv3 must be configured, and the attacker must share its broadcast domain; a restart drops every OSPFv3 adjacency until recovery.

CVSS severity7.0
High
EPSS probability0.21%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Reachable assertion in the Ospf3 agent in Arista EOS allows remote attackers to interrupt OSPFv3 routing with crafted packets. The agent accepts a specially crafted packet sequence from its broadcast domain and reaches an assertion that restarts the process. OSPFv3 must be configured, and the attacker must share its broadcast domain; a restart drops every OSPFv3 adjacency until recovery.

The record

CVE
CVE-2026-73438
Published
Sep 16, 2026
Updated
Sep 16, 2026
Vendor
Arista Networks
Product
Arista EOS
Classifications
CWE-617, T1499.004
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

5.3Arista NetworksCVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:N/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-617Reachable Assertion
T1499.004Application or System Exploitation

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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