An issue was discovered on COROS PACE 3 devices through 3.0808.0. It implements a function to connect the watch to a WLAN. This function is mainly for downloading firmware files. Before downloading firmware files, the watch requests some information about the firmware via HTTPS from the back-end API. However, the X.509 server certificate within the TLS handshake is not validated by the device. This allows an attacker within an active machine-in-the-middle position, using a TLS proxy and a self-signed certificate, to eavesdrop and manipulate the HTTPS communication. This could be abused, for example, for stealing the API access token of the assigned user account.
The product does not validate, or incorrectly validates, a certificate.