The OKLOK (3.1.1) mobile companion app for Fingerprint Bluetooth Padlock FB50 (2.3) has an information-exposure issue. In the mobile app, an attempt to add an already-bound lock by its barcode reveals the email address of the account to which the lock is bound, as well as the name of the lock. Valid barcode inputs can be easily guessed because barcode strings follow a predictable pattern. Correctly guessed valid barcode inputs entered through the app interface disclose arbitrary users' email addresses and lock names.