A vulnerability was found in the app 2.0 of the Shenzhen Jisiwei i3 robot vacuum cleaner, while adding a device to the account using a QR-code. The QR-code follows an easily predictable pattern that depends only on the specific device ID of the robot vacuum cleaner. By generating a QR-code containing information about the device ID, it is possible to connect an arbitrary device and gain full access to it. The device ID has an initial "JSW" substring followed by a six digit number that depends on the specific device.