Is it recommended to use the $HTTP_REFERER variable when appending variables to a header location in PHP?

Using the $HTTP_REFERER variable to append variables to a header location in PHP is not recommended as it can be easily manipulated by the user and may pose security risks. It is better to sanitize and validate user input before using it in header locations to prevent potential vulnerabilities such as header injection attacks. 

// Sanitize and validate user input before appending it to the header location
$userInput = filter_input(INPUT_GET, 'user_input', FILTER_SANITIZE_STRING);

if ($userInput) {
    // Redirect to the desired location with sanitized user input
    header("Location: https://example.com/page.php?user_input=" . urlencode($userInput));
    exit();
} else {
    // Handle invalid input or redirect to a default location
    header("Location: https://example.com/default.php");
    exit();
}

Keywords

$HTTP_REFERER header location variables PHP security

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