What are common pitfalls when using PHP sessions to manage user authentication in a forum setting?

Common pitfalls when using PHP sessions to manage user authentication in a forum setting include not properly validating user input, not securely storing session data, and not properly destroying sessions after logging out. To solve these issues, always validate user input to prevent injection attacks, use secure methods to store session data (such as using HTTPS), and ensure sessions are properly destroyed after logging out.

// Start the session
session_start();

// Validate user input
$username = filter_input(INPUT_POST, 'username', FILTER_SANITIZE_STRING);
$password = filter_input(INPUT_POST, 'password', FILTER_SANITIZE_STRING);

// Securely store session data
$_SESSION['username'] = $username;

// Destroy session after logging out
session_destroy();