Auth bypass in Broadcom Rabbitmq Server
CVE-2026-67411
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.
Vulnerability class: Broken Access Control
Published · last modified .
CVSS v3 metric
CVSS v3 base score 7.1 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:N.
EPSS exploit prediction
EPSS: 0.003 (24.9th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 25th percentile — 24.9% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.003 · newest: 0.003 · change: 0.000
Affected products
- Broadcom Rabbitmq Server
- Rabbitmq Rabbitmq-Server — versions >= 3.13.0, < 3.13.18, >= 4.0.0, < 4.0.23, >= 4.1.0, < 4.1.14
Weakness classification (CWE)
References
- https://github.com/rabbitmq/rabbitmq-server/security/advisories/GHSA-4r6f-9cpw-f6g6 (Exploit, Vendor Advisory)
- https://github.com/rabbitmq/rabbitmq-server/commit/a7528314840c4f8dc9904684f9f97ffa7aac6349 (Patch)
- https://github.com/rabbitmq/rabbitmq-server/commit/edbead0eabbd65925d0dc914a22d6a29e155e646 (Patch)
- https://github.com/rabbitmq/rabbitmq-server/releases/tag/v4.2.9 (Release Notes)
- https://github.com/rabbitmq/rabbitmq-server/releases/tag/v4.3.3 (Release Notes)
Frequently asked questions
- What is CVE-2026-67411?
- CVE-2026-67411 is a high-severity vulnerability in Broadcom Rabbitmq Server, classified under Incorrect Authorization. CVSS score: 7.1/10. Published 2026-09-25.
- How severe is CVE-2026-67411?
- High severity. CVSS v3 base score is 7.1 out of 10.