OpenClaw versions before 2026.3.13 contain a resource exhaustion vulnerability in their Telegram webhook implementation. The application reads and buffers webhook request bodies before validating the x-telegram-bot-api-secret-token header, allowing unauthenticated attackers to exhaust server resources. Attackers can exploit this by sending POST requests to the webhook endpoint, forcing memory consumption, socket time usage, and JSON parsing work before authentication occurs. This design flaw enables denial-of-service attacks against OpenClaw installations using Telegram webhooks.