Access Confluence Knowledge Base from Service Desk Help Center shows empty window!?

[Markus Raab]

I have a problem and no idea how to solve it. If I try to search for knowledge base articles from JIRA Service Desk I can find them, but if I want to open them I only get a white popup window without any content.

What could be the reason for that?

[Markus Raab]

Found myself a first hint to the solution: 

https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/X-Frame-Options

JIRA Service Desk = service.companyname.com

Confluence Knowledge Base = community.companyname.com

But I am still confused. Is it not possible to enable the full access to the Confluence knowledge base articles from Service Desk's Help Center in a secure way?

Obviously I need to change something on the server which increases vulnerability.