Bug 2541531 (CVE-2026-67411)

Summary: CVE-2026-67411 rabbitmq-server: rabbitmq-server: Access control bypass via PROXY protocol handling in MQTT
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
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 native Message Queuing Telemetry Transport (MQTT) or MQTT over WebSockets operates behind a trusted proxy utilizing the PROXY protocol, the broker may drop the client IP address before enforcing user restriction checks. This failure causes external connections to be incorrectly identified as local loopback traffic. A remote attacker with valid credentials for an account restricted to local access can exploit this flaw to bypass source-address restrictions and connect remotely.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Description OSIDB Bzimport 2026-09-25 16:53:39 UTC
RabbitMQ is a messaging and streaming broker. From 3.13.0 until 3.13.18, 4.0.23, 4.1.14, 4.2.9, and 4.3.3, native MQTT and MQTT over WebSocket behind a trusted PROXY Protocol frontend could lose the proxy-derived client address before the MQTT authentication path checked loopback_users, causing the frontend-to-broker address to be treated as loopback. An attacker who can reach the trusted frontend and has valid credentials for a loopback-restricted account can therefore bypass the source-address restriction; the issue does not bypass password authentication. This issue is fixed in versions 3.13.18, 4.0.23, 4.1.14, 4.2.9, and 4.3.3.