What are the potential security risks associated with using PHP to preload and download files on the client's machine?

One potential security risk associated with using PHP to preload and download files on the client's machine is the possibility of malicious files being downloaded without the user's consent. To mitigate this risk, it is important to validate the file path and ensure that only authorized files can be downloaded. 

<?php
$allowed_files = array("file1.pdf", "file2.jpg", "file3.txt");
$file = $_GET['file'];

if (in_array($file, $allowed_files)) {
    $filepath = '/path/to/files/' . $file;
    header('Content-Type: application/octet-stream');
    header('Content-Disposition: attachment; filename="' . basename($filepath) . '"');
    readfile($filepath);
} else {
    echo 'Unauthorized file access.';
}
?>

Keywords

PHP file download security risks client-side preloading

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