What are the potential pitfalls of using hidden input fields in HTML forms to pass data between PHP pages?

One potential pitfall of using hidden input fields in HTML forms to pass data between PHP pages is that the data can be easily manipulated by a user, leading to security vulnerabilities or incorrect data being processed. To mitigate this risk, it is recommended to use server-side validation and verification of the data being passed.

// Validate and sanitize the data received from the hidden input field
$hidden_data = isset($_POST['hidden_data']) ? $_POST['hidden_data'] : '';
$validated_data = validate_data($hidden_data);

function validate_data($data) {
    // Implement your validation logic here
    // For example, check if the data is in a specific format or matches certain criteria
    return $validated_data;
}