The Primakon Pi Portal 1.0.18 /api/V2/pp_users?email endpoint is used for user data filtering but lacks proper server-side validation against the authenticated session. By manipulating the email parameter to an arbitrary value (e.g., otheruser@user.com), an attacker can assume the session and gain full access to the target user's data and privileges. Also, if the email parameter is left blank, the application defaults to the first user in the list, who is typically the application administrator, resulting in an immediate Privilege Escalation to the highest level.