Academist Membership <= 1.1.6 - Authentication Bypass via Account Takeover

The Academist Membership plugin for WordPress is vulnerable to Privilege Escalation in all versions up to, and including, 1.1.6. This is due to the academist_membership_check_facebook_user() function not properly verifying a user's identity prior to authenticating them. This makes it possible for unauthenticated attackers to log in as any user, including site administrators.