What potential issues should be considered when allowing users to navigate through directories using PHP?

One potential issue when allowing users to navigate through directories using PHP is the risk of directory traversal attacks, where users could access sensitive files outside of the intended directory. To prevent this, it's crucial to sanitize user input and restrict their access to only specific directories. Additionally, it's important to validate user input to ensure they are not attempting to access unauthorized directories. 

$base_dir = '/var/www/html/uploads/';
$requested_dir = isset($_GET['dir']) ? $_GET['dir'] : '';

$full_path = realpath($base_dir . $requested_dir);

if (strpos($full_path, $base_dir) !== 0) {
    die('Invalid directory access.');
}

// Rest of the code to display files in the directory

Keywords

directory traversal security vulnerabilities open_basedir restriction realpath() scandir()

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