Backend API does not properly validate the input

[tobice]

Some backend API methods (i.e. for creating user accountt) do not properly validate the input. For example, it is theoretically possible to create an empty user account (with all fields empty).

Given the overall application nature and the state it's currently in, this does not present a real problem (we are no aware of any actual vulnerability). The current solution for authentication and authorization should be replaced (or extended) with something more robust anyway.