2.2.0.0 Error 403 while updating specific products

Hello everyone.
I get a 403 error when I try to update an existing product.

You don't have permission to access /.../admin/index.php on this server

This does not happen with all products.
Do you have any ideas what happens over there?

Could be a firewall security rule beeing triggered, due to the content you are trying to add (links or iframes in the description). Enquire your hoster about it.