What are the potential pitfalls of not properly handling session IDs in PHP?

Improper handling of session IDs in PHP can lead to security vulnerabilities such as session hijacking or fixation. To mitigate these risks, it is crucial to properly generate, validate, and destroy session IDs in PHP. This can be achieved by setting session.cookie_httponly to true to prevent client-side scripts from accessing the session cookie, using session_regenerate_id() to generate a new session ID after successful authentication, and calling session_destroy() to invalidate the session when the user logs out.

// Set session cookie to be accessible only through HTTP
ini_set('session.cookie_httponly', 1);

// Start the session
session_start();

// Regenerate session ID after successful authentication
if ($authenticated) {
    session_regenerate_id();
}

// Destroy the session when the user logs out
session_destroy();