ElasticSearch allows only GET requests

Hi guys,

two days ago I upgraded my ES cluster to the latest 2.3.0 version.
Today somehow the cluster started to refuse all POST, PUT, DELETE requests, and allows only GET requests.
I use postman to play with the API and I've never seen this before.

I asked our IT guys about what if they messed up some firewall settings but they sad they did nothing.

What can I do now?

Problem was at my client node config: "http.cors.enabled" option has to be deleted.
More details here: https://github.com/elastic/kibana/issues/6719