CVE-2026-67420: RabbitMQ OAuth credential refresh retains revoked runtime tags

Severity: medium (CVSS 6.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.3% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2026-09-25 · updated 2026-10-16
Weakness: CWE-862

Description

RabbitMQ is a messaging and streaming broker. From 3.13.0 until 3.13.19, 4.0.24, 4.1.15, 4.2.10, and 4.3.5, RabbitMQ OAuth credential refresh retains revoked runtime tags. when an existing AMQP connection refreshes from an OAuth token that grants the impersonator tag to a valid same-username token that no longer grants that tag, RabbitMQ updates the OAuth backend implementation (token/scopes/expiry) but leaves the connection's runtime #user.tags unchanged. rabbitaccesscontrol:checkuserid/2 then still honors the stale impersonator tag, so the connection (including newly opened channels) can continue publishing messages with a foreign AMQP userid after that privilege should have been revoked. A fresh connection using the downgraded token correctly refuses the same publish, proving the defect is stale session state rather than the token Limited to connections that once held impersonator and successfully refresh to a downgraded same-username rabbitauthbackendoauth2 (or an equivalent refresh-capable backend that returns tags) is enabled for This issue is fixed in versions 3.13.19, 4.0.24, 4.1.15, 4.2.10, and 4.3.5.

Affected products

rabbitmq-server: from 3.13.0 before 3.13.19; from 4.0.0 before 4.0.24; from 4.1.0 before 4.1.15; from 4.2.0 before 4.2.10; from 4.3.0 before 4.3.5 — fixed in 3.13.19, 4.0.24, 4.1.15, 4.2.10, 4.3.5

How to fix

Upgrade to a fixed version: rabbitmq-server 3.13.19, 4.0.24, 4.1.15, 4.2.10. Check the vendor advisory for mitigations.

References

Get alerted when CVE-2026-67420 or the next vulnerability affects your stack