https://tools.ietf.org/html/draft-ietf-httpbis-rfc6265bis-02

We choose Lax and not Strict so that we can open links to ERP5 from
external applications and so that OAuth Logins work. Implementing the
"two cookies, one for read one for write" approach suggested in
https://tools.ietf.org/html/draft-ietf-httpbis-rfc6265bis-02#section-8.8.2
would be too big change at this point.