What are some common mistakes to avoid when handling user authentication and authorization in PHP applications?

One common mistake to avoid when handling user authentication and authorization in PHP applications is not properly sanitizing user input before using it in SQL queries, which can lead to SQL injection attacks. To prevent this, always use prepared statements with parameterized queries to securely interact with the database. 

// Incorrect way of querying the database without using prepared statements
$username = $_POST['username'];
$password = $_POST['password'];
$sql = "SELECT * FROM users WHERE username='$username' AND password='$password'";
$result = $conn->query($sql);

// Correct way of using prepared statements to prevent SQL injection
$username = $_POST['username'];
$password = $_POST['password'];
$stmt = $conn->prepare("SELECT * FROM users WHERE username=? AND password=?");
$stmt->bind_param("ss", $username, $password);
$stmt->execute();
$result = $stmt->get_result();

Keywords

SQL injection password hashing session management CSRF protection role-based access control

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