Imagine you are building an order checkout system inside a Telegram Mini App using React. When a user opens your application inside their mobile client, Telegram injects an embedded WebView context exposing the global window.Telegram.WebApp object. React developers often jump straight into building UI components by pulling user profile details directly from window.Telegram.WebApp.initDataUnsafe.user .

If you send this initDataUnsafe user ID directly to your API to look up accounts, process orders, or issue rewards, your application is completely vulnerable to identity spoofing. Because Mini Apps are standard web applications running inside an embedded browser frame, anyone can open your Mini App's URL in a standard desktop browser, open Developer Tools, and mutate window.Telegram.WebApp.initDataUnsafe to contain any target user ID.…