hello,
I have a similar problem.
I get in my logs
xxxx – – [xxxx /May/2017] “POST /wp-admin/admin-ajax.php HTTP/1.1” 200 1 “https://xxxx/wp-admin/admin-ajax.php” “Opera/9.80 (Windows NT 6.0) Presto/2.12.388 Version/12.14”
xxxx – – [xxxx /May/2017:xxxx +xxxx ] “POST /wp-login.php?action=register HTTP/1.1” 302 – “xxxx /wp-login.php?action=register” “Opera/9.80 (Windows NT 6.0) Presto/2.12.388 Version/12.14”
xxxx – – [xxxx /May/2017:xxxx 4 +xxxx ] “GET /wp-login.php?checkemail=registered HTTP/1.1” 200 4307
I have disabled user registration, also I have plugin Disable User Registration, I have plugin Disable Password Reset. but the above user managed to register as admin in my site.
What else can I do?