Google are starting to enforce stricter cookie handling in Chrome 80 next week. In researching this change it appears iOS 12 and below and macOS 10.14 and below have a core networking issue that prevents proper handling of the "Samesite=none" cookie attribute.
It's reported that older versions of CFNetwork/Safari/Webkit erroneously handle "Samesite=none" as the equivalent of "Samesite=strict". This might have big consequences as web service providers start using the Samesite attribute more widely.
There are details in the Webkit bug 198181 (now resolved) thread here: https://bugs.webkit.org/show_bug.cgi?id=198181
Part way down is a reference to a CFNetwork/NSHTTPCookie fix for this issue under rdar://problem/42290578.
However, other comments indicate that this fix is unlikely to be back ported to previous macOS & iOS versions.
Does anyone have a definitive answer as to whether iOS 11/12 and macOS 10.13/10.14 will recieve a fix for the cookie Samesite handling issue?