Telegram Mini Apps Need Server-Side Verification to Prevent User ID Spoofing

Developers building Telegram Mini Apps often trust the user ID from the client-side initDataUnsafe object, which an attacker can alter to impersonate another user. Such a design can expose private order histories, drain balances, or let attackers change database records. The article recommends treating initDataUnsafe as untrusted and instead sending the raw initData string to a PHP backend. There, the server verifies the HMAC-SHA256 signature with the bot token, checks the auth_date timestamp, and issues a short-lived JWT. The React frontend then uses that token in Authorization headers for all later API calls.