What are the security considerations when using GET parameters to change website content in PHP?

When using GET parameters to change website content in PHP, it is important to validate and sanitize the input to prevent security vulnerabilities such as SQL injection or cross-site scripting attacks. One way to address this issue is by using prepared statements and parameterized queries when interacting with a database. Additionally, you can use PHP's filter_input function to sanitize user input before using it in your code. 

// Example of sanitizing input from GET parameters
$user_id = filter_input(INPUT_GET, 'user_id', FILTER_SANITIZE_NUMBER_INT);

// Using prepared statements to prevent SQL injection
$stmt = $pdo->prepare('SELECT * FROM users WHERE id = :id');
$stmt->bindParam(':id', $user_id, PDO::PARAM_INT);
$stmt->execute();

// Displaying the user's information
$user = $stmt->fetch();
echo 'User ID: ' . $user['id'] . '<br>';
echo 'Username: ' . htmlspecialchars($user['username']);

Keywords

PHP GET parameters security SQL injection cross-site scripting

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