In openEQUELLA before 2026.1, the GET /api/userquery/userinfobackup endpoint performs no authentication or authorisation check. An unauthenticated attacker who supplies another user's uniqueId can retrieve that user's stored personal details (username, first name, last name and email address) within the same institution.
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.