The diagnostics web interface in the Yeahlink Ultra-elegant IP Phone SIP-T41P (firmware 66.83.0.35) does not validate (escape) the path information (path traversal), which allows an authenticated remote attacker to get access to privileged information (e.g., /etc/passwd) via path traversal (relative path information in the file parameter of the corresponding POST request).

A CSRF (Cross Site Request Forgery) in the web interface of the Yeahlink Ultra-elegant IP Phone SIP-T41P firmware version 66.83.0.35 allows a remote attacker to trigger code execution or settings modification on the device by providing a crafted link to the victim.

The network diagnostic function (ping) in the Yeahlink Ultra-elegant IP Phone SIP-T41P (firmware 66.83.0.35) allows a remote authenticated attacker to trigger OS commands or open a reverse shell via command injection.