If you deploy a Telegram bot endpoint in pure PHP without strict request verification, your system is vulnerable to two distinct failure modes: unauthorized actors sending forged payloads directly to your server, and duplicate update execution caused by Telegram's retry mechanism.

Imagine a Telegram bot handling automated lead capturing or inventory allocation. If your webhook URL is publicly accessible, an attacker who discovers your endpoint path can send fake JSON payloads impersonating users, triggering invalid transactions or polluting your database. Conversely, if your server experiences a temporary database latency spike and delays returning an HTTP 200 response, Telegram's servers will timeout, consider the delivery failed, and retry sending the exact same payload multiple times.…