Improper access control in RabbitMQ Server - CVE-2026-67420
Published: August 18, 2026
Vulnerability details
The vulnerability allows a remote user to publish messages with a foreign AMQP user_id after that privilege should have been revoked.
The vulnerability exists due to improper access control in rabbit_access_control:update_state/2 and rabbit_access_control:check_user_id/2 when refreshing an existing AMQP connection from an OAuth token that no longer grants the impersonator tag. A remote user can refresh the connection with a same-username token that omits the impersonator tag to publish messages with a foreign AMQP user_id after that privilege should have been revoked.
Only connections that previously held the impersonator tag are affected. The issue requires a refresh-capable OAuth backend for AMQP, a successful credential refresh before the original credential-expiry timer closes the connection, and it affects both existing and newly opened channels on the refreshed connection.