The plugin does not validate and escapes some of its shortcode attributes before outputting them back in the page, which could allow users with a role as low as a contributor to perform Stored Cross-Site Scripting attacks, which could be used against high privilege users such as admins.
Exploit shortcode:
[content_control class='xss" onmouseover="alert(1)" style="background:red;width:100px;height:100px;" data-more-class="']