SameSite None

Meaning

SameSite=None is a value that allows the cookie on all requests, including cross-site ones. It is needed for legitimate cross-site uses such as an embedded widget, a payment frame or an identity provider on another domain. MDN states that the Secure attribute must be set with it, and current browsers reject the cookie otherwise. A correct header is Set-Cookie: widget=xyz; Secure; SameSite=None. It reopens the exposure SameSite was built to close, and it does not guarantee delivery where third-party cookies are blocked. See also: Secure, Third-party cookie, Partitioned cookie, the guide "SameSite Strict, Lax and None Explained".