Traccar Client is a GPS tracking mobile app for sending location updates to private servers using the open-source Traccar platform. In versions 9.7.19 and below, a single crafted deep link can silently hijack all GPS tracking parameters and redirect telemetry to an attacker-controlled server. The app registers a custom org.traccar.client://config deep-link scheme that silently writes attacker-supplied parameters (server URL, device ID, accuracy, distance, and interval) into the app's persistent configuration with no confirmation, notification, or visual indication. A single crafted link delivered via SMS, email, a webpage, or any installed app can therefore reconfigure the app the moment the victim taps it, with no special permissions required. As a result, an attacker can covertly redirect all of the victim's GPS telemetry to their own server at maximum precision and frequency, and the change persists across restarts. This gives the attacker continuous, real-time tracking of the victim's location. This issue has been fixed in version 9.7.20.