WP Admin UI Customize < 1.5.13 - Admin+ Stored XSS

The plugin does not sanitise and escape some of its settings, which could allow high privilege users such as admin to perform Stored Cross-Site Scripting attacks even when the unfiltered_html capability is disallowed (for example in multisite setup).

PoC

1. Go to “WP Admin UI Customize” » “Login Form”. 2. Enter the following value in the first four input boxes: 123" onmouseenter=alert(/XSS/) ". 3. Click the ‘Save’ button on the page. 4. Refresh or re-enter the page and move the mouse over the input box to get the XSS to trigger.