An issue was discovered on TK-Star Q90 Junior GPS horloge 3.1042.9.8656 devices. It performs actions based on certain SMS commands. This can be used to set up a voice communication channel from the watch to any telephone number, initiated by sending a specific SMS and using the default password, e.g., pw,<password>,call,<mobile_number> triggers an outbound call from the watch. The password is sometimes available because of CVE-2019-20471.
https://www.eurofins-cybersecurity.com/news/connected-devices-smart-watches/