ProfilePress < 3.1.11 - Unauthenticated Cross-Site Scripting (XSS) in tabbed login/register widget

1. Add the registration shortcode to a page.
2. Add the tabbed login/register widget on the same page.
3. Visit the page logged out and add this to the end of the URL /?tabbed-login-name="><script>alert(1)</script>

This could also be replicated by posting to any page with the widget present, which would not need the registration shortcode to be present on the page.