CVE-2026-67411: Broadcom Rabbitmq Server

High severity, CVSS 7.1. EPSS: 0.3% chance of exploitation in the next 30 days.

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.

Affected products

• Broadcom Rabbitmq Server: from 3.13.0, before 3.13.18 (fixed in 3.13.18); from 4.0.0, before 4.0.23 (fixed in 4.0.23); from 4.1.0, before 4.1.14 (fixed in 4.1.14); from 4.2.0, before 4.2.9 (fixed in 4.2.9); from 4.3.0, before 4.3.3 (fixed in 4.3.3)

Published 2026-09-25. Last modified 2026-10-08.