Laravel Reverb provides a real-time WebSocket communication backend for Laravel applications. Prior to 1.4.0, there is an issue where verification signatures for requests sent to Reverb's Pusher-compatible API were not being verified. This API is used in scenarios such as broadcasting a message from a backend service or for obtaining statistical information (such as number of connections) about a given channel. This issue only affects the Pusher-compatible API endpoints and not the WebSocket connections themselves. In order to exploit this vulnerability, the application ID which, should never be exposed, would need to be known by an attacker. This vulnerability is fixed in 1.4.0.

Laravel Reverb Missing API Signature Verification