The MashShare WordPress plugin before 3.8.7 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/96e34d3d-627f-42f2-bfdb-c9d47dbf396c