Using beginning of TLS ecnrypted data to reveal secret I have the following question about TLS security:

Assume TLS-PSK protected HTTP with AES256-CBC cipher. 
When a TLS connection is established, client sends some encrypted data, where the
plaintext is well known to an attacker.

For example, it can be a HTTP request, like:

GET /some_resource HTTP/1.1
...


Can an attacker use intercepted ciphertext and known plaintext it to reveal the secret key?

Does TLS have any features to protect from that?
This question boils down to, "Are there known-plaintext attacks against AES-256-CBC?" The answer is: No, no such attacks better than brute force are known. This would constitute a catastrophic break in AES-256-CBC, and any cipher broken in such a way would be abandoned rapidly.