The Mesmerize Companion WordPress plugin before 1.6.135 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/9dc9d377-635d-4d4f-9916-33bcedbba6f0