The Paid Memberships Pro – Content Restriction, User Registration, & Paid Subscriptions plugin for WordPress is vulnerable to Cross-Site Request Forgery in all versions up to, and including, 2.12.10. This is due to missing nonce validation on the pmpro_lifter_save_streamline_option() function. This makes it possible for unauthenticated attackers to enable the streamline setting with Lifter LMS via a forged request granted they can trick a site administrator into performing an action such as clicking on a link.