What are the potential security risks associated with including subpages in a PHP system via URL parameters?

Including subpages in a PHP system via URL parameters can potentially lead to security risks such as injection attacks or unauthorized access to sensitive information. To mitigate these risks, it is important to properly sanitize and validate the input from URL parameters before using it in the system. 

// Sanitize and validate the subpage parameter
$subpage = isset($_GET['subpage']) ? $_GET['subpage'] : 'default';
$subpage = filter_var($subpage, FILTER_SANITIZE_STRING);

// Include the subpage content only if it exists in a predefined list
$allowed_subpages = ['page1', 'page2', 'page3'];
if (in_array($subpage, $allowed_subpages)) {
    include($subpage . '.php');
} else {
    include('error.php');
}

Keywords

SQL injection cross-site scripting URL parameters input validation security vulnerabilities

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