What security considerations should be kept in mind when dealing with file paths in PHP?

When dealing with file paths in PHP, it is important to sanitize and validate user input to prevent directory traversal attacks. Always validate file paths against a whitelist of allowed directories and filenames to ensure that only legitimate paths are accessed. Additionally, use PHP's built-in functions like realpath() to resolve and normalize file paths to prevent any unexpected behavior. 

$user_input = $_GET['file_path'];
$allowed_paths = ['/path/to/allowed_directory/'];

$real_path = realpath($user_input);

if(in_array($real_path, $allowed_paths)) {
    // Process the file
} else {
    // Handle invalid file path
}

Keywords

file paths security PHP validation injection

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