What are the best practices for handling user input and data transfer in PHP to prevent potential vulnerabilities?

To prevent potential vulnerabilities when handling user input and data transfer in PHP, it is essential to sanitize and validate all incoming data to prevent SQL injection, cross-site scripting (XSS), and other attacks. Use prepared statements or parameterized queries when interacting with databases to prevent SQL injection. Additionally, implement input validation to ensure that only expected data types and formats are accepted. 

// Example of sanitizing user input to prevent SQL injection
$userInput = $_POST['user_input'];
$cleanedInput = mysqli_real_escape_string($connection, $userInput);

// Example of validating user input to prevent XSS
$userInput = $_POST['user_input'];
$cleanedInput = htmlspecialchars($userInput, ENT_QUOTES, 'UTF-8');

// Example of using prepared statements to prevent SQL injection
$stmt = $connection->prepare("SELECT * FROM users WHERE username = ?");
$stmt->bind_param("s", $username);
$username = $_POST['username'];
$stmt->execute();

Keywords

SQL injection cross-site scripting data validation input sanitization prepared statements

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