Parse Server is an open source backend that can be deployed to any infrastructure that can run Node.js. In versions prior to 4.10.15, or 5.0.0 and above prior to 5.2.6, a user can write to the session object of another user if the session object ID is known. For example, an attacker can assign the session object to their own user by writing to the `user` field and then read any custom fields of that session object. Note that assigning a session to another user does not usually change the privileges of either of the two users, and a user cannot assign their own session to another user. This issue is patched in version 4.10.15 and above, and 5.2.6 and above. To mitigate this issue in unpatched versions add a `beforeSave` trigger to the `_Session` class and prevent writing if the requesting user is different from the user in the session object.
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, prior to versions 4.10.14 or 5.2.5, returns a response object. The patch available in versions 4.10.14 and 5.2.5 requires the maser 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.
Parse Server is an open source backend that can be deployed to any infrastructure that can run Node.js. In affected versions parse Server LiveQuery does not remove protected fields in classes, passing them to the client. The LiveQueryController now removes protected fields from the client response. Users are advised to upgrade. Users unable t upgrade should use `Parse.Cloud.afterLiveQueryEvent` to manually remove protected fields.