The Trackr device ID is constructed of a manufacturer identifier of four zeroes followed by the BLE MAC address in reverse. The MAC address can be obtained by being in close proximity to the Bluetooth device, effectively exposing the device ID. The ID can be used to track devices. Updated apps, version 5.1.6 for iOS and 2.2.5 for Android, have been released by the vendor to address the vulnerabilities in CVE-2016-6538, CVE-2016-6539, CVE-2016-6540 and CVE-2016-6541.