Are third parties cookies sent with image requests from first party web pages

We have an implementation understanding with a merchant to create our domain cookies when user is on his site. Now in FF assuming 开发者_开发问答that third party cookies acceptance is set we are able to create the cookies and flow works fine. But the issue is that after the cookie is created and third party cookie is disabled later - the request to load an image from merchant site page to ours site - we do not receive the cookie details.

Is it an expected behavior or we need some special mechanism to get the cookie?

Please help.

You may already know this but cookies are domain based. You can only access cookies on requests for the same domain.

If your image is displayed on sample.com and your the url of the image is sample.com/img.jpg then when the request is made for the image the cookies will be sent along with the request.

On the other hand if the image is displayed on sample.com and the image url is yoursite.com/img.jpg then you won't receive the cookies for sample.com.

Also, dev.sample.com and sample.com are different domain names.

Hopefully this helps clarify why you can't receive cookies. This behavior is mainly security related to prevent websites from sniffing cookies from other sites.