Exposure of Sensitive Information to an Unauthorized Actor

Summary

Parse Server is an open-source backend that can be deployed to any infrastructure that can run Node.js. Internal fields (keys used internally by Parse Server, prefixed by `_`) and protected fields (user-defined) can be used as query constraints. Internal and protected fields are removed by Parse Server and are only returned to the client using a valid master key. However, using query constraints, these fields can be guessed by enumerating until Parse Server, versions prior to 4.10.14, 5.0.x prior to 5.2.5, and 5.3.x prior to 5.3.0-alpha.22 return a response object. The patch available in versions 4.10.14, 5.2.5, and 5.3.0-alpha.22 requires the master key to use internal and protected fields as query constraints. As a workaround, implement a Parse Cloud Trigger `beforeFind` and manually remove the query constraints.