Is FastCGI secure?

Question

Nginx

Hello. Please help me understand the situation.
There is a web service:
Client ---(https)---> NGINX(Proxy) ---(fastCGI)---> WebApplication.
As you can see, a secure connection is used from the client to the proxy server (user data is transmitted), but fastCGI further to the web application, how will the data be transmitted? Encrypted or not? After all, a web application can be physically located on a different server than a proxy, and the transfer in unencrypted form from one machine to another is a vulnerability. Or am I missing something?)
Thank you in advance for your answers.

Answer 1

FastCGI has no mission to be secure. Usually it is used within the same machine and the issue of protocol security is not at all worth it.
If you need to use it over a network, then its security must be ensured in the same way as the security of any other network connection. For example, by raising an encrypted channel between servers.