Perhaps this is what they were talking about: https://www.cvedetails.com/cve/CVE-2019-13640/

> In qBittorrent before 4.1.7, the function Application::runExternalProgram() located in app/application.cpp allows command injection via shell metacharacters in the torrent name parameter or current tracker parameter, as demonstrated by remote command execution via a crafted name within an RSS feed.