We are having problems with Safari(and Opera) and from what I have read the FedAuth cookies are just too big.
There is an \"neat trick\" to fix this: \"WIF RTM added a p
Old thread, but I believe SessionSecurityTokenCreated is the proper event to handle this--tested it and it works under "old WIF" and NET 4.5 with the appropriate namespace variations.
void WSFederationAuthenticationModule_SessionSecurityTokenCreated(object sender, System.IdentityModel.Services.SessionSecurityTokenCreatedEventArgs e)
{
e.SessionToken.IsReferenceMode = true;
}