Restrict Usernames Emails Characters Plugin < 3.1.4 - Admin+ Stored XSS

Description The plugin does not sanitise and escape some of its settings, which could allow high privilege users such as admin to perform Cross-Site Scripting attacks even when unfiltered_html is disallowed

PoC

1. Access the “Restrict Usernames Emails Characters” settings 2. For the field “The name of the user_login field in registration form”, enter the payload ">![](1) 3. Click “Save Changes” and see the XSS.