Nezha Monitoring is a self-hostable, lightweight, servers and websites monitoring and O&M tool. From version 1.4.0 to before version 2.0.9, any authenticated non-admin member can connect to the server-status WebSocket and receive telemetry for all servers, including servers owned by other users. The normal server list API filters objects by HasPermission, but the WebSocket stream treats the presence of any authenticated user as authorization for the full unfiltered server list. This issue has been patched in version 2.0.9.