LavinMQ, a high‑performance message queue and streaming server, contains a flaw that allows an authenticated user to view broker metadata they should not have access to. This leads to unauthorized disclosure of broker metadata. The weakness corresponds to missing vhost access control (CWE-862).

The vulnerability affects Cloudamqp LavinMQ deployments running any version earlier than 2.6.6. Attackers with valid credentials, irrespective of the vhost they belong to, may exploit the flaw to read metadata outside their intended namespace. Versions 2.6.6 and later include a fix that enforces proper vhost isolation.

The CVSS v3.1 score is 7.1, indicating a high severity. EPSS indicates the likelihood of exploitation is very low (< 1%), and the flaw is not listed in CISA’s KEV catalog. Exploitation requires authenticated access, so the attacker must first compromise a user account. Once authenticated, the attacker can query metadata across vhosts, potentially revealing information beyond the intended namespace.