RabbitMQ up to 4.2.7/4.3.1 Authentication Mechanism get_auth_mechanism input validation

Summaryinfo

A vulnerability, which was classified as problematic, was found in RabbitMQ up to 4.2.7/4.3.1. This impacts the function get_auth_mechanism of the component Authentication Mechanism. Such manipulation leads to input validation. This vulnerability is uniquely identified as CVE-2026-67234. The attack can be launched remotely. No exploit exists. You should upgrade the affected component.

Detailsinfo

A vulnerability was found in RabbitMQ up to 4.2.7/4.3.1 and classified as problematic. Affected by this issue is the function get_auth_mechanism of the component Authentication Mechanism. The manipulation with an unknown input leads to a input validation vulnerability. Using CWE to declare the problem leads to CWE-20. The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly. Impacted is integrity. CVE summarizes:

RabbitMQ is a messaging and streaming broker. From 4.2.0 until 4.2.8 and 4.3.2, get_auth_mechanism/1 used term_to_binary/1 on the strict_auth_mechanism or preferred_auth_mechanism atom when clearing the corresponding cookie, producing a non-ASCII cookie name that violates RFC 6265 and can prevent the browser from deleting the preference. The issue is not directly exploitable for code execution or data exfiltration; its security relevance is limited to stale authentication-mechanism preferences persisting across logout and login cycles. This issue is fixed in versions 4.2.8 and 4.3.2.

The advisory is available at github.com. This vulnerability is handled as CVE-2026-67234 since 07/28/2026. The exploitation is known to be easy. The attack may be launched remotely. Successful exploitation requires user interaction by the victim. Technical details are known, but there is no available exploit.

Upgrading to version 4.2.8 or 4.3.2 eliminates this vulnerability.

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Productinfo

Name

• RabbitMQ

Version

• 4.2.0
• 4.2.1
• 4.2.2
• 4.2.3
• 4.2.4
• 4.2.5
• 4.2.6
• 4.2.7
• 4.3.0
• 4.3.1

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