Social Sharing Toolkit <= 2.6 - Contributor+ Stored XSS via Shortcode

The plugin 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.

PoC

Note: First you need to enable some social sharing in Social Sharing Toolkit Settings. You can find this setting in the Shortcode tab. Exploit shortcode: [social_share url=‘" onmouseover=“alert(1)”’]