The WP Membership plugin 1.2.3 for WordPress allows remote authenticated users to gain administrator privileges via an iv_membership_update_user_settings action to wp-admin/admin-ajax.php.
https://wpvulndb.com/vulnerabilities/7998
http://www.securityfocus.com/bid/74766
http://www.securityfocus.com/archive/1/535652/100/0/threaded
http://www.securityfocus.com/archive/1/535587/100/0/threaded