What best practices should be followed when using PHP to handle form submissions securely?

When handling form submissions securely in PHP, it is important to validate and sanitize user input to prevent SQL injection and cross-site scripting attacks. Additionally, use prepared statements when interacting with a database to avoid SQL injection vulnerabilities. Lastly, consider implementing CSRF tokens to prevent cross-site request forgery attacks. 

// Validate and sanitize user input
$username = filter_var($_POST['username'], FILTER_SANITIZE_STRING);
$email = filter_var($_POST['email'], FILTER_VALIDATE_EMAIL);

// Use prepared statements to interact with the database
$stmt = $pdo->prepare("INSERT INTO users (username, email) VALUES (:username, :email)");
$stmt->bindParam(':username', $username);
$stmt->bindParam(':email', $email);
$stmt->execute();

// Implement CSRF tokens
$token = bin2hex(random_bytes(32));
$_SESSION['csrf_token'] = $token;

// Include the CSRF token in the form
<input type="hidden" name="csrf_token" value="<?php echo $token; ?>">

Keywords

SQL injection cross-site scripting prepared statements data validation CSRF protection

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