# CVE-2026-66067: RabbitMQ stream protocol connection limit bypass

Source: https://junglewise.ai/threats/cve-2026-66067-rabbitmq-is-a-messaging-and-streaming-broker-prior-to-versions-4  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-09-23. Updated: 2026-09-26  
License: CC BY 4.0 with a link back

CVE-2026-66067 · Severity: info · Published 2026-09-23

RabbitMQ is a message broker that organizations use to queue and route messages between systems. When the stream protocol plugin is enabled, authenticated users can bypass operator-configured limits on concurrent connections per user or virtual host, allowing them to create unlimited connections and potentially monopolize broker resources or cause denial of service.

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

## Quick answers

**Is CVE-2026-66067 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-66067 being exploited in the wild.

**How severe is CVE-2026-66067?** Informational severity, published 23 September 2026.

**Which products and versions are affected?** RabbitMQ prior to 4.2.7 and 4.3.1.

**Is there a fix for CVE-2026-66067?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-66067 attacked?** It is attacked over the network, in a hosted service.

**Am I affected by CVE-2026-66067?** 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

The stream protocol open handler in RabbitMQ prior to 4.2.7 and 4.3.1 only calls check_vhost_access but omits the per-user and per-vhost connection-limit checks that the AMQP protocol enforces. An authenticated attacker with stream-protocol credentials connecting via port 5552 instead of 5672 can bypass these limits. The vulnerability requires the rabbitmq_stream plugin to be enabled and relies on operators using connection limits for tenant isolation.

## Affected products

- RabbitMQ RabbitMQ prior to 4.2.7 and 4.3.1

## Timeline

- 2026-09-23: disclosed

## References

- [https://github.com/rabbitmq/rabbitmq-server/releases/tag/v4.2.7](https://github.com/rabbitmq/rabbitmq-server/releases/tag/v4.2.7)
- [https://github.com/rabbitmq/rabbitmq-server/releases/tag/v4.3.1](https://github.com/rabbitmq/rabbitmq-server/releases/tag/v4.3.1)

## 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 MQTT loopback user bypass via PROXY Protocol](https://junglewise.ai/threats/cve-2026-67411-rabbitmq-is-a-messaging-and-streaming-broker-from-3-13-0-until-3)
- [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)