XSS exists in PRTG Network Monitor 20.1.56.1574 via crafted map properties. An attacker with Read/Write privileges can create a map, and then use the Map Designer Properties screen to insert JavaScript code. This can be exploited against any user with View Maps or Edit Maps access.
https://www.paessler.com/prtg/history/stable
https://gist.github.com/alert3/e058baa33c31695f4168a1dbf77103df