The vulnerability stems from unsanitized filename rendering in the File Manager's web interface. The exploit requires filenames to be displayed without proper encoding, which points directly to the directory listing functionality. In Ajenti's architecture, the FileManagerHandler class likely handles file/directory operations, and its directory listing method would be responsible for passing raw filenames to the UI template. The absence of HTML entity encoding in this data flow matches the described XSS attack vector via crafted filenames.