The LearnPress – WordPress LMS Plugin plugin for WordPress is vulnerable to bypass to user registration in versions up to, and including, 4.2.6.5. This is due to missing checks in the 'create_account' function in the checkout. This makes it possible for unauthenticated attackers to register as the default role on the site, even if registration is disabled.
https://plugins.trac.wordpress.org/changeset/3082204/
https://plugins.trac.wordpress.org/browser/learnpress/tags/4.2.6.5/inc/class-lp-checkout.php#L79