Parse Server is an open source backend that can be deployed to any infrastructure that can run Node.js. From version 9.8.0 to before version 9.9.1-alpha.5, apps that enable MFA and deny get on the _User class via Class-Level Permissions could expose sensitive user data through the /login and /verifyPassword endpoints. These endpoints re-fetch the user through the access-controlled query pipeline (CLP, protectedFields, auth-adapter sanitizers) before responding. When that re-fetch was denied by the _User get permission, the server fell back to the raw database row, exposing raw authData (including MFA TOTP secrets and recovery codes) and fields hidden by protectedFields (when protectedFieldsOwnerExempt is false). /verifyPassword is the most severe: with only a username and password (no session or MFA token), an attacker who knows a victim's password could retrieve their MFA secret and recovery codes, defeating the second factor. This issue has been patched in version 9.9.1-alpha.5.