	wp.updates.keydown = function( event ) {
		if ( 27 === event.keyCode ) {
			wp.updates.requestForCredentialsModalCancel();
		} else if ( 9 === event.keyCode ) {

			// #upgrade button must always be the last focus-able element in the dialog.
			if ( 'upgrade' === event.target.id && ! event.shiftKey ) {
				$( '#hostname' ).focus();

				event.preventDefault();
			} else if ( 'hostname' === event.target.id && event.shiftKey ) {
				$( '#upgrade' ).focus();

				event.preventDefault();
			}
		}
	};
The web application does not, or can not, sufficiently verify whether a well-formed, valid, consistent request was intentionally provided by the user who submitted the request.