CVE-2026-66067: rabbitmq rabbitmq-server

Vulnerability summary

CVE-2026-66067 is a medium (CVSS 6.0) vulnerability in rabbitmq rabbitmq-server. EPSS estimates a 0.35% chance of exploitation in the next 30 days, higher than 27.2% of scored vulnerabilities.

Timeline

1. 23-09-2026
   PublishedVulnerability first disclosed.
2. 24-09-2026
   Last modifiedVulnerability information updated.

Description

RabbitMQ is a messaging and streaming broker. Prior to versions 4.2.7 and 4.3.1, The stream open handler calls only check_vhost_access; it omits the node/vhost/user connection-limit checks that rabbit_reader performs for AMQP. A developer %% FIXME comment at the cited line explicitly acknowledges the gap. No compensating enforcement exists in connection tracking or elsewhere in rabbitmq_stream. An authenticated tenant can fully bypass operator-configured per-user and per-vhost connection caps by connecting via port 5552 instead of 5672. Preconditions include rabbitmq_stream plugin enabled Authenticated stream-protocol credentials Operator relies on per-user/per-vhost connection limits for tenant isolation. This issue is fixed in versions 4.2.7 and 4.3.1.

• CWE-770Allocation of Resources Without Limits or ThrottlingThe product allocates a reusable resource or group of resources on behalf of an actor without imposing any intended restrictions on the size or number of resources that can be allocated.