The plugin does not sanitise and escape its settings, allowing high privilege users such as admin to perform cross-Site Scripting attacks even when the unfiltered_html capability is disallowed.
1. In the settings of the plugin, in the three input boxes are named “Second Address Label”, “Login Logo Override”, and “Custom CRM Header”, enter the payload: 1" onmouseenter=alert(1) " 2. Refresh the page and hover the mouse on the input boxes to get the XSS trigger.