# CVE-2026-67420: RabbitMQ OAuth privilege escalation via stale token tags

Source: https://junglewise.ai/threats/cve-2026-67420-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-2026-67420 · Severity: info · Published 2026-09-25

RabbitMQ is a messaging broker used to route and deliver messages between applications. When using OAuth for authentication, a security flaw allowed connections to retain elevated privileges (the "impersonator" tag) even after an administrator revoked them by downgrading the user's token. An attacker with a revoked token could continue publishing messages with unauthorized user identities until they reconnected, creating a window for unauthorized message injection and privilege abuse.

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

## Quick answers

**Is CVE-2026-67420 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-67420 being exploited in the wild.

**How severe is CVE-2026-67420?** Informational severity, published 25 September 2026.

**Which products and versions are affected?** RabbitMQ 3.13.0 to 3.13.18, 4.0.0 to 4.0.23, 4.1.0 to 4.1.14, 4.2.0 to 4.2.9, 4.3.0 to 4.3.4.

**Is there a fix for CVE-2026-67420?** A patch was published on 2026-08-17: Fixed in RabbitMQ 3.13.19, 4.0.24, 4.1.15, 4.2.10, 4.3.5 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-67420 attacked?** It is attacked over the network, in a hosted service.

**Am I affected by CVE-2026-67420?** 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 vulnerability exists in OAuth credential refresh logic (rabbitaccesscontrol:checkuserid/2): when an existing AMQP connection refreshes an OAuth token that no longer grants the impersonator tag, RabbitMQ updates the backend token/scopes/expiry but fails to rebuild the connection's runtime user.tags. The stale impersonator tag remains in the connection state, allowing the attacker to publish with a foreign AMQP userid. The defect is limited to refresh-capable OAuth backends and requires the connection to have once held impersonator privileges. Fresh connections using the downgraded token correctly refuse the same operation.

## Affected products

- RabbitMQ RabbitMQ 3.13.0 to 3.13.18, 4.0.0 to 4.0.23, 4.1.0 to 4.1.14, 4.2.0 to 4.2.9, 4.3.0 to 4.3.4

## Timeline

- 2026-09-25: disclosed
- 2026-08-17: patched: Fixed in RabbitMQ 3.13.19, 4.0.24, 4.1.15, 4.2.10, 4.3.5

## References

- [https://github.com/rabbitmq/rabbitmq-server/commit/5de287d213765ca592ff5848ad2f6b9b98ee6772](https://github.com/rabbitmq/rabbitmq-server/commit/5de287d213765ca592ff5848ad2f6b9b98ee6772)
- [https://github.com/rabbitmq/rabbitmq-server/releases/tag/v4.3.5](https://github.com/rabbitmq/rabbitmq-server/releases/tag/v4.3.5)

## Related threats

- [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)
- [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)