BAN Users <= 1.5.3 - Subscriber+ Settings Update & Privilege Escalation via Missing Authorization

Description

The plugin is vulnerable to privilege escalation in versions up to, and including, 1.5.3 due to a missing capability check on the 'w3dev_save_ban_user_settings_callback' function. This makes it possible for authenticated attackers, with minimal permissions such as a subscriber, to modify the plugin settings to access the ban and unban functionality and set the role of the unbanned user.