Parse Server has an auth provider validation bypass on login via partial authData

Impact

An authentication bypass vulnerability allows an attacker to log in as any user who has linked a third-party authentication provider, without knowing the user's credentials. The attacker only needs to know the user's provider ID to gain full access to their account, including a valid session token.

This affects Parse Server deployments where the server option allowExpiredAuthDataToken is set to true. The default value is false.

Patches

Auth providers are now always validated on login, regardless of the allowExpiredAuthDataToken setting. The option allowExpiredAuthDataToken has been deprecated and will be removed in a future major version.

Workarounds

Set allowExpiredAuthDataToken to false (the default) or remove the option from the server configuration.