Paid Membership Plugin < 4.15.20 - Admin+ Stored XSS

The Paid Membership Plugin, Ecommerce, User Registration Form, Login Form, User Profile & Restrict Content WordPress plugin before 4.15.20 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).