What are the best practices for handling user input like $_GET in PHP to prevent security vulnerabilities?

When handling user input like $_GET in PHP, it is important to sanitize and validate the input to prevent security vulnerabilities such as SQL injection or cross-site scripting attacks. One common practice is to use functions like filter_input() or htmlentities() to sanitize the input and validate it against expected values. Additionally, using prepared statements when interacting with databases can help prevent SQL injection attacks. 

// Sanitize and validate user input from $_GET
$user_input = filter_input(INPUT_GET, 'user_input', FILTER_SANITIZE_STRING);

// Validate against expected values
$allowed_values = ['value1', 'value2', 'value3'];
if (!in_array($user_input, $allowed_values)) {
    // Handle invalid input
}

// Use prepared statements when interacting with databases
$stmt = $pdo->prepare("SELECT * FROM table WHERE column = :user_input");
$stmt->bindParam(':user_input', $user_input);
$stmt->execute();

Keywords

filter_input htmlspecialchars prepared statements SQL injection cross-site scripting

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