Parse Server is an open source backend that can be deployed to any infrastructure that can run Node.js. Prior to 9.5.2-alpha.3 and 8.6.16, class-level permissions (CLP) are not enforced for LiveQuery subscriptions. An unauthenticated or unauthorized client can subscribe to any LiveQuery-enabled class and receive real-time events for all objects, regardless of CLP restrictions. All Parse Server deployments that use LiveQuery with class-level permissions are affected. Data intended to be restricted by CLP is leaked to unauthorized subscribers in real time. This vulnerability is fixed in 9.5.2-alpha.3 and 8.6.16.