# CVE-2026-67407: RabbitMQ MQTT topic permission bypass in regex escaping

Source: https://junglewise.ai/threats/cve-2026-67407-rabbitmq-is-a-messaging-and-streaming-broker-from-4-0-0-until-4-3  
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-2026-67407 · Severity: info · Published 2026-09-25

RabbitMQ is a messaging broker that handles MQTT communications. An incomplete security fix allows low-privileged authenticated MQTT users to bypass topic permission restrictions by crafting a clientid that breaks out of character class patterns in permission templates. This could allow unauthorized read and write access to message topics that should be restricted.

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

## Quick answers

**Is CVE-2026-67407 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-67407 being exploited in the wild.

**How severe is CVE-2026-67407?** Informational severity, published 25 September 2026.

**Which products and versions are affected?** VMware RabbitMQ 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-2026-67407?** 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-2026-67407 attacked?** It is attacked over the network.

**Am I affected by CVE-2026-67407?** Check whether you run VMware 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 escaperegexchar/1 function fails to escape the hyphen (-) character when constructing regex patterns for MQTT topic permissions, despite fixing other metacharacters for CVE-2026-44838. An authenticated attacker controlling their clientid can inject regex syntax when templates embed {clientid} inside a [...] character class, bypassing intended permission boundaries. Patches are available in versions 4.3.3, 4.2.9, 4.1.14, and 4.0.23.

## Affected products

- VMware RabbitMQ 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

## References

- [https://github.com/rabbitmq/rabbitmq-server/releases/tag/v4.2.9](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/releases/tag/v4.3.3)

## Related threats

- [RabbitMQ MQTT 5 parser invalid property denial of service](https://junglewise.ai/threats/cve-2026-67418-rabbitmq-is-a-messaging-and-streaming-broker-from-3-13-0-until-3)
- [RabbitMQ AMQP 1.0 parser descriptor validation bypass](https://junglewise.ai/threats/cve-2026-67416-rabbitmq-is-a-messaging-and-streaming-broker-from-4-0-0-until-4-0)
- [RabbitMQ AMQP 1.0 parser memory exhaustion](https://junglewise.ai/threats/cve-2026-67414-rabbitmq-is-a-messaging-and-streaming-broker-from-4-0-0-until-4-0)
- [RabbitMQ Management XSS via queue name in OAuth UI](https://junglewise.ai/threats/cve-2026-67421-rabbitmq-is-a-messaging-and-streaming-broker-from-3-13-0-until-3)
- [RabbitMQ JMS topic exchange denial of service via regex wildcard expansion](https://junglewise.ai/threats/cve-2026-67413-rabbitmq-is-a-messaging-and-streaming-broker-from-4-0-0-until-4-0)