What potential issues can arise when combining PHP code to display transferred values in a specific field?

One potential issue that can arise when combining PHP code to display transferred values in a specific field is improper handling of user input, leading to security vulnerabilities like SQL injection or cross-site scripting. To solve this, always validate and sanitize user input before displaying it on the webpage to prevent these security risks.

// Example of validating and sanitizing user input before displaying it in a specific field
$user_input = $_POST['user_input']; // Assuming the transferred value is stored in $_POST['user_input']

// Validate and sanitize user input
$validated_input = filter_var($user_input, FILTER_SANITIZE_STRING);

// Display the sanitized input in a specific field
echo '<input type="text" value="' . $validated_input . '">';