Hi Flabbes.
This is an Chrome / Xenforo issue, that is causing the browser XXS Auditor to block the request.
Basically, when you try to edit a post, that has a reference to the forum, it will give this error.
I have instructed Mariandor about this and how to work around it.
Just a head's up: We will archive this as "not a bug" because it's not a game bug which our game development team can solve. The feedback has been forwarded however.