The Simple Sitemap WordPress plugin before 3.5.8 does not validate and escape some of its shortcode attributes before outputting them back in the page, which could allow users with a role as low as contributor to perform Stored Cross-Site Scripting attacks which could be used against high privilege users such as admins.
https://wpscan.com/vulnerability/2b685a12-2ca3-42dd-84fe-4a463a082c2a