Invitation Based Registrations <= 2.2.84 - Admin+ Stored Cross-Site Scripting

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 when the unfiltered_html capability is disallowed (for example in multisite setup)

PoC

Put the following payload in the “After Register Redirect URL” Advanced Settings of the plugin: "autofocus onfocus=alert(/XSS/)//