auditing-message-broker-topic-authorization

name	auditing-message-broker-topic-authorization
description	Audit message-broker topic and queue authorization for reach a client should not have: a wildcard subscription that receives another tenant's messages, a publish permission broad enough to inject into a control or command topic, a shared broker where topic naming is the only separation between tenants, and a client authenticated to the broker but not authorized per topic so any connection can read or write any topic. Covers MQTT, Kafka, AMQP, and similar brokers where publish and subscribe permissions on topics or queues are the boundary between producers, consumers, and tenants. Use when a broker carries messages across trust boundaries and topic-level authorization is the control. The client publishing or subscribing is the source, the topic or queue it reaches is the sink, and the wildcard or missing per-topic authorization that admits it is the bug.
license	MIT

Auditing message-broker topic authorization: when a wildcard subscribes to everyone

A message broker is a shared channel that many producers and consumers, often many tenants, talk through, and topic authorization is what keeps one client's messages from reaching another's. That boundary is thinner than it looks. Authenticating to the broker is not the same as being authorized per topic: a broker that checks the connection but not the topic lets any authenticated client read or write any topic. Wildcards make it worse, a subscription with a wildcard can match another tenant's topics and receive their messages, and a broad publish permission can inject into a control or command topic that consumers act on. And on a shared broker, topic naming is frequently the only thing separating tenants, which is a convention, not an enforced boundary. The audit asks, for each client, exactly which topics it can publish to and subscribe to, and whether that matches its role. You audit this by enumerating effective topic permissions and testing cross-tenant reach.