The Document Gallery WordPress plugin before 5.1.1 does not properly sanitise and escape user input before reflecting it back in the response of an unauthenticated AJAX action, leading to a Reflected Cross-Site Scripting vulnerability which can be exploited against unauthenticated users.
https://wpscan.com/vulnerability/a3c279ce-5db1-4331-ad74-4eef49619737/