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.
What this means for your business
What to do
- 1Ask your IT team or provider whether any of your systems use the affected product.
- 2If you do, follow the vendor's guidance. No patch reference has been published yet.
Fastnexa security experts
Not sure if your company is exposed to CVE-2026-67411?
Tell us where you run the affected software and a Fastnexa penetration tester will check whether this flaw, or others like it, can be used against your websites, apps and network.
The full test is free for our first 10 founding clients until 31 December 2026. See the offer
Think you’ve already been hit? Don’t wait on a form: call or WhatsApp +1 (732) 454 2616. We reply within 1 hour, 24/7. Emergency help →
Scoring
- CVSS
- Not yet scored
- CVSS v4
- 6.0
- Weakness
- CWE-863
- Assigned by
- security-advisories@github.com
Dates
- Published
- 2026-09-25
- Last modified
- 2026-09-28
- Sources
- NVD
References
- https://github.com/rabbitmq/rabbitmq-server/commit/a7528314840c4f8dc9904684f9f97ffa7aac6349
- https://github.com/rabbitmq/rabbitmq-server/commit/edbead0eabbd65925d0dc914a22d6a29e155e646
- https://github.com/rabbitmq/rabbitmq-server/releases/tag/v4.2.9
- https://github.com/rabbitmq/rabbitmq-server/releases/tag/v4.3.3
- https://github.com/rabbitmq/rabbitmq-server/security/advisories/GHSA-4r6f-9cpw-f6g6