The Buttons Shortcode and Widget WordPress plugin through 1.16 does not validate and escape some of its shortcode attributes before outputting them back in a page/post where the shortcode is embed, which could allow users with the contributor role and above to perform Stored Cross-Site Scripting attacks.
https://wpscan.com/vulnerability/8e286c04-ef32-4af0-be78-d978999b2a90/