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.

Multiple cross-site scripting (XSS) vulnerabilities in Local Phone book and Blacklist form in Yealink VOIP Phones allow remote authenticated users to inject arbitrary web script or HTML via the user field to cgi-bin/ConfigManApp.com.