Authorization Bypass Through User-Controlled Key
this vulnerability affect user that even not allowed to access via the web interface. First of all, the attacker needs to access the "Login menu - demo site" then he can see in this menu all the functionality of the application. If the attacker will try to click on one of the links, he will get an answer that he is not authorized because he needs to log in with credentials. after he performed log in to the system there are some functionalities that the specific user is not allowed to perform because he was configured with low privileges however all the attacker need to do in order to achieve his goals is to change the value of the prog step parameter from 0 to 1 or more and then the attacker could access to some of the functionality the web application that he couldn't perform it before the parameter changed.
CWE-639 - Authorization Bypass Through User-Controlled Key
The system's authorization functionality does not prevent one user from gaining access to another user's data or record by modifying the key value identifying the data.