SameSite
changes, how to test to see if your site is impacted and how to fix it.SameSite
and why the big change?SameSite
Chrome flags and test to see if your site faces SameSite
errorsSameSite
and why the big change?SameSite
.a.com
and you attempt to access a service from the same domain name a.com
, cookies generated will be considered first-party cookies. Being that the cookies were created by the same site, you'll be able to enjoy same-site luxuries while visiting a.com
's web service. These luxuries include saved login information, shopping cart items, site preferences, etc.a.com
but that page includes content (image, iframe, etc.) from a different domain name b.com
, cookies set by b.com
will be considered third-party cookies because they come from a different name than in the URL bar: a.com
.b.com
accessing them from a.com
(or any other domain) would constitute a cross-site request. A page on a.com
making requests to b.com
(for images, iframes, etc.) is what allows services like Facebook, Google Analytics, Doubleclick, etc. to track users and provide online-advertisements. In that example, Facebook, Google, and Doubleclick are the b.com
. This allows, for example, Doubleclick to show targeted ads to you on multiple other sites you visit, like a news site, a hotel site, or a blog you read.SameSite
. In other words, the content from b.com
(images, iframe, etc.) on a.com
’s page will no longer be able to access b.com
's cookies unless those cookies are secured and flagged appropriately.POST
request for money transfers. It would be impossible to create a malicious request using an <a href>
tag. This attacker could very well create a <form>
tag instead with automatic execution of the embedded JavaScript.SameSite
attribute Strict
(read more below), banks have yet another preventive measure. Large companies have found methods of protection; however, there are lots of smaller websites without protection. If an attacker can forge a transaction, they can also forge a password reset request, an email change request, and then gain full control of an account or web application.SameSite
attribute can be set with the following values: Strict
, Lax
, or None
.Strict
completely blocks a cookie being sent to a.com
when a page from b.com
makes the request. Even when clicking a top-level link on a third-party domain to your site, the browser will refuse to send the cookie. This option would be best for applications that require high security, such as banks.None
where cookies are always sent, Lax
cookies are only sent on same-site request like Strict
. However, Lax
allows top-level (sometimes called public suffix) navigation access with a safe HTTP method, like HTTP GET
. The cookie will not be sent with cross-domain POST
requests or when loading the site in a cross-origin frame, but it will be sent when you navigate to the site via a standard top-level <a href=..>
link.None
and Secure
attributes together. If you just specify None
without Secure
the cookie will be rejected. Secure
ensures that the browser request is sent by a secure (HTTPS) connection.Strict
and Lax
None
attribute is pretty understandable; however, there seems to be confusion around Strict
and Lax
. Let's dive into a real-world example.Lax
, your customers are still able to access their embedded comments. If TalkToMe, Inc.'s first-party cookies are set to Strict
, your customers will not be able to access data from an external site.SameSite
updateSameSite=Lax
by default. In other words, Chrome has decided to make all cookies limited to first-party context by default, and will require developers to mark a cookie as needing third-party visibility using SameSite=None
explicitly.SameSite
update requires explicit labeling for third-party cookies. Cookies that aren’t labeled appropriately may cease to function in Chrome. Even more than that: all cookies previously set may no longer be accessible.SameSite
Chrome flags and test to see if your site faces potential SameSite
errors#same-site-by-default-cookies
flag and test your site before the February 4, 2020 deadline.SameSite
attribute will be treated as SameSite=Lax
(See variants below), meaning all cookies will be restricted to first-party context only. If you need third-party access, you will need to update your cookies.SameSite=None; Secure
to enable access.<iframe>
.SameSite
attributes:Value | Description |
---|---|
Strict | Cookies with this setting can be accessed only when visiting the domain from which it was initially set. In other words, Strict completely blocks a cookie being sent to a.com when it is being sent from a page on b.com (i.e. b.com is in the URL bar). Even when clicking a top-level link on a third-party domain to your site, the browser will refuse to send the cookie. This option would be best for applications that require high security, such as banks. |
Lax | Unlike None where cookies are always sent, Lax cookies are only sent on same-site request like Strict . However, Lax allows top-level navigation access with a safe HTTP method, like HTTP GET . The cookie will not be sent with cross-domain POST requests or when loading the site in a cross-origin frame, but it will be sent when you navigate to the site via a standard top-level <a href=..> link. |
None | Cookies with this setting will work the same way as cookies work today. Cookies will be able to be used across sites. ?Note that you need both the None and Secure attributes together. If you just specify None without Secure the cookie will be rejected. Secure ensures that the browser request is sent by a secure (HTTPS) connection. |
SameSite=Strict
SameSite=Lax
SameSite=None; Secure
When to.. | Scenario | Attribute | If you do nothing |
---|---|---|---|
Use SameSite=Strict | Your website offers banking services or your website needs a very secure environment | Update your SameSite attribute to SameSite=Strict to add a layer of protection from web threats. | Your site may be susceptible to potential web vulnerabilities and data leaks. |
Use SameSite=Lax | You have a social community website and you offer embedded chat widgets | Update your SameSite attribute to SameSite=Lax | You'll be good to go. Chrome's default behavior will be SameSite=Lax . Even if SameSite is not set, the default is still SameSite=Lax |
Use SameSite=None | Your website offers data analytics services OR your website offers retargeting, advertising and conversion tracking. | Update your SameSite attribute to SameSite=None; Secure to ensure Chrome doesn't reject your third-party cookies. | Your cookies will no longer work on Feb 4, 2020. |
'Speak to a representative' | You've monetized your website with third-party ad programs OR you're utilizing third-party services like Google Calendar, Cloudflare, Facebook, Twitter, Instagram, LinkedIn, Gravatar, User Tracking services, CRM, reservations plugin, anti-fraud, third-party fonts, image/video hosting and/or payments services. | Speak with the ad program company to ensure they have a plan to update their cookies. You can't update cookies on a domain you don't control. | You may see a decline in the ad revenue you receive and or business engagement. |
SameSite
attributes; however, there are a few clients who don't support it (see Known Incompatible Clients).SameSite=None
in languages, libraries, and frameworksdocument.cookie
SameSite
examples repo on GitHub.SameSite
cookies] issue template.SameSite
updates page.