CVE-2026-5768 Details

A vulnerability exists in the Fourth Frontier Frontier X2 device, allowing unauthenticated Bluetooth Low Energy (BLE) read/write access to critical GATT characteristics. This flaw bypasses pairing authentication and authorization, enabling attackers within BLE range to gain unauthorized control over device functions. Exploitation can involve starting or stopping activities, triggering vibrations, creating denial-of-service conditions, and fuzzing characteristic values to provoke unexpected behavior. Furthermore, the associated Frontier X mobile application lacks adequate BLE device authentication. This deficiency permits attackers to impersonate a legitimate Frontier X2 device and connect to the application. By cloning BLE advertisements and presenting expected GATT characteristics, attackers can manipulate activity states and inject fabricated health telemetry, such as breathing rate, heart rate, strain, and other health-related data, into the mobile application.

Fourth Frontier is aware of the vulnerability and is working on a fix. Users are encouraged to contact Fourth Frontier directly for assistance. The Frontier X/X2 devices can connect to only one app at a time; users should first connect the device using the Frontier X app and then start the activity.