Arista EOS up to 4.37.0F RIPv2 MD5 Authentication improper authorization

Summaryinfo

A vulnerability classified as critical was found in Arista EOS up to 4.37.0F. The affected element is an unknown function of the component RIPv2 MD5 Authentication. The manipulation results in improper authorization. This vulnerability is identified as CVE-2026-121288. The attack can be executed remotely. There is not any exploit available. Upgrading the affected component is advised.

Detailsinfo

A vulnerability was found in Arista EOS up to 4.37.0F. It has been classified as critical. Affected is an unknown function of the component RIPv2 MD5 Authentication. The manipulation with an unknown input leads to a improper authorization vulnerability. CWE is classifying the issue as CWE-285. The product does not perform or incorrectly performs an authorization check when an actor attempts to access a resource or perform an action. This is going to have an impact on integrity, and availability. CVE summarizes:

An unauthenticated attacker on an adjacent network segment can bypass MD5 authentication and have unauthorized RIP route updates accepted by the device. Successful exploitation requires that RIPv2 MD5 authentication is configured on the affected interface. An attacker who can inject crafted RIPv2 packets could cause the device to install routes that redirect network traffic through attacker-controlled paths, create routing loops, or blackhole traffic, disrupting network connectivity.

The advisory is shared for download at arista.com. This vulnerability is traded as CVE-2026-121288 since 11/03/2026. The exploitability is told to be easy. It is possible to launch the attack remotely. The exploitation doesn't require any form of authentication. There are neither technical details nor an exploit publicly available. The MITRE ATT&CK project declares the attack technique as T1548.002.

Upgrading to version 4.32.0F or 4.33.0F eliminates this vulnerability.

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Productinfo

Vendor

• Arista

Name

• EOS

Version

• 4.0
• 4.1
• 4.2
• 4.3
• 4.4
• 4.5
• 4.6
• 4.7
• 4.8
• 4.9
• 4.10
• 4.11
• 4.12
• 4.13
• 4.14
• 4.15
• 4.16
• 4.17
• 4.18
• 4.19
• 4.20
• 4.21
• 4.22
• 4.23
• 4.24
• 4.25
• 4.26
• 4.27
• 4.28
• 4.29
• 4.30
• 4.31
• 4.32
• 4.33.10M
• 4.34.8M
• 4.35.6M
• 4.36.2F
• 4.37.0F

License

• commercial

CPE 2.3info

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CPE 2.2info

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