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CVE-2026-121288VulnerabilityPublished

An unauthenticated attacker on an adjacent network segment can bypass MD5 authentication and have unauthorized RIP

Source GCVE Database

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Authoritative record:CVE-2026-121288· High 8.1

Not known to be exploited · CVSS 8.1 High : upgrade to 4.33.0F or 4.32.0F soon.

Data as of 10 Nov 2026, 23:19 UTC

CVSS 3.1 base score
8.1High
How severe the flaw is on the 0–10 CVSS scale.

Thin evidence

One scorer or none
CVSS scores by source
CNA (Arista)CVSS 3.18.1
CNA (Arista)CVSS 4.06.1
Patch
Available – fixed in 4.33.0F, 4.32.0F
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:H/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
  • =4.37.0F
Fixed in
  • 4.33.0F
  • 4.32.0F

AI-suggested

If you cannot patch yet, network administrators should consider disabling RIPv2 MD5 authentication on interfaces exposed to untrusted adjacent networks or implement additional network segmentation and monitoring to detect anomalous RIP traffic.

Description

This vulnerability allows an unauthenticated attacker on an adjacent network segment to bypass MD5 authentication for RIPv2 route updates if MD5 authentication is configured on the interface. The attacker can inject crafted RIPv2 packets that the device accepts, potentially causing unauthorized route installation. This can lead to traffic redirection through attacker-controlled paths, routing loops, or blackholing of traffic, disrupting network connectivity.

References

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