In FusionPBX up to v4.5.7, the file app\contacts\contact_import.php uses an unsanitized "query_string" variable coming from the URL, which is reflected in HTML, leading to XSS.
https://resp3ctblog.wordpress.com/2019/10/19/fusionpbx-xss-17/
https://github.com/fusionpbx/fusionpbx/commit/ccdb27536d3549b5c0c317e3665fff231631ec77