The User Profile Builder WordPress plugin before 4.0.5 does not sanitise and escape one of its shortcode attributes before outputting it back in a redirect message, which could allow users with a role as low as contributor to perform Stored Cross-Site Scripting attacks against higher-privileged users who submit the affected form.
https://wpscan.com/vulnerability/26983c21-09d2-491f-b62f-1270b335dfcd/