Bug 2541504 (CVE-2026-67234)

Summary: CVE-2026-67234 rabbitmq-server: rabbitmq-server: Authentication preference persistence via invalid cookie name
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: low Docs Contact:
Priority: low    
Version: unspecifiedCC: eglynn, jjoyce, jpretori, jschluet, lhh, mburns, mgarciac
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in rabbitmq-server. When clearing authentication preferences, the server generates a non-compliant cookie name containing invalid characters that standard web browsers reject when attempting deletion. This issue prevents the browser from properly removing the cookie, allowing stale authentication-mechanism preferences to unintentionally persist across logout and login cycles.
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Description OSIDB Bzimport 2026-09-25 16:42:36 UTC 
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.