In FusionPBX up to v4.5.7, the file app\xml_cdr\xml_cdr_delete.php uses an unsanitized "rec" variable coming from the URL, which is base64 decoded and allows deletion of any file of the system.
https://resp3ctblog.wordpress.com/2019/10/19/fusionpbx-path-traversal-1/
https://github.com/fusionpbx/fusionpbx/commit/284b0a91968f126fd6be0a486a84e065926905ca