Markup <= 4.8.1 - Contributor+ Stored XSS via Shortcode

The plugin 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.

PoC

[wp-structuring-markup-breadcrumb class=‘" onmouseover=“alert(1)”’] Note: If we add the shortcode to a page, select another page as “parent” so that the breadcrumb appears.