GS Logo Slider < 3.3.8 - Contributor+ Stored XSS in 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

Exploit shortcode: [gs_logo id=‘" onmouseover=“alert(1)” style=“background:red;width:100px;height:100px;”’]