Popup box < 3.8.6 - Admin+ Stored XSS in Popup Settings

Description 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. Add a new Popup 2. In the “Popups > Settings” section, add the PoC "> for any of the “Close Button” parameters. 3. Save and navigate back to the popups and see the XSS.