@Jeemusu 's answers provides a solution, though a few comments and another suggested solution after reading: https://discussions.apple.com/thread/4156939?tstart=0
- To me, this has nothing with preventing CSRF, other browsers are not preventing this, I would say that this is more related with preventing tracking.
- The page at Apple suggests the following: the problem only occures when the iframe domain has not been visited first (and this is what I have observed).
- One solution would be for the caller domain to set a cookie when a user arrives, redirect to the called domain to "count as a visit" and then redirect back to the called domain (that would read the first set cookies to not redirect again).
I would say that disabling CSRF protection is an unsecure idea.