# CVE-2026-67411: RabbitMQ MQTT loopback user bypass via PROXY Protocol

Source: https://junglewise.ai/threats/cve-2026-67411-rabbitmq-is-a-messaging-and-streaming-broker-from-3-13-0-until-3  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-09-25. Updated: 2026-09-26  
License: CC BY 4.0 with a link back

CVE-2026-67411 · Severity: info · Published 2026-09-25

RabbitMQ is a message broker that enterprises use for reliable message queuing and streaming. When deployed behind a PROXY Protocol frontend, the MQTT protocol handler could lose the client's real IP address before checking whether the connection is from a restricted loopback-only account. An attacker with valid credentials for such an account could bypass the source-address restriction and connect from the network, though password authentication is still required.

Technologies: [RabbitMQ](https://junglewise.ai/threats/technologies/rabbitmq-rabbitmq). Vendors: [RabbitMQ](https://junglewise.ai/threats/vendors/rabbitmq).

## Quick answers

**Is CVE-2026-67411 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-67411 being exploited in the wild.

**How severe is CVE-2026-67411?** Informational severity, published 25 September 2026.

**Which products and versions are affected?** RabbitMQ 3.13.0 to 3.13.17, 4.0.0 to 4.0.22, 4.1.0 to 4.1.13, 4.2.0 to 4.2.8, 4.3.0 to 4.3.2.

**Is there a fix for CVE-2026-67411?** A patch was published on 2026-07-15: Fixes cherry-picked to maintenance branches; versions 3.13.18, 4.0.23, 4.1.14, 4.2.9, 4.3.3 released Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-67411 attacked?** It is attacked over the network, in a hosted service.

**Am I affected by CVE-2026-67411?** Check whether you run RabbitMQ at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

RabbitMQ's native MQTT and WebSocket MQTT implementations fail to preserve the proxy-derived client address through the full authentication path, causing the loopback_users check to receive the frontend-to-broker address instead. An attacker with network access to the trusted PROXY Protocol frontend and valid credentials for a loopback-restricted user can bypass source-address restrictions. Password authentication is still enforced; this is a source-address bypass only.

## Affected products

- RabbitMQ RabbitMQ 3.13.0 to 3.13.17, 4.0.0 to 4.0.22, 4.1.0 to 4.1.13, 4.2.0 to 4.2.8, 4.3.0 to 4.3.2

## Timeline

- 2026-09-25: disclosed
- 2026-07-15: patched: Fixes cherry-picked to maintenance branches; versions 3.13.18, 4.0.23, 4.1.14, 4.2.9, 4.3.3 released

## References

- [https://github.com/rabbitmq/rabbitmq-server/commit/a7528314840c4f8dc9904684f9f97ffa7aac6349](https://github.com/rabbitmq/rabbitmq-server/commit/a7528314840c4f8dc9904684f9f97ffa7aac6349)
- [https://github.com/rabbitmq/rabbitmq-server/commit/edbead0eabbd65925d0dc914a22d6a29e155e646](https://github.com/rabbitmq/rabbitmq-server/commit/edbead0eabbd65925d0dc914a22d6a29e155e646)

## Related threats

- [RabbitMQ OAuth privilege escalation via stale token tags](https://junglewise.ai/threats/cve-2026-67420-rabbitmq-is-a-messaging-and-streaming-broker-from-3-13-0-until-3)
- [RabbitMQ topic exchange denial of service via duplicate matchers](https://junglewise.ai/threats/cve-2026-67419-rabbitmq-is-a-messaging-and-streaming-broker-prior-to-4-3-5-an)
- [RabbitMQ Shovel denial of service via atom exhaustion](https://junglewise.ai/threats/cve-2026-67415-rabbitmq-is-a-messaging-and-streaming-broker-from-4-2-0-until-4-2)
- [RabbitMQ OAuth2 client secret exposure via unauthenticated endpoint](https://junglewise.ai/threats/cve-2026-67410-rabbitmq-is-a-messaging-and-streaming-broker-from-4-2-0-until-4-3)
- [RabbitMQ JWKS fetch ignores HTTP response status code](https://junglewise.ai/threats/cve-2026-67409-rabbitmq-is-a-messaging-and-streaming-broker-from-3-13-0-until-4)