Cannot read cookie in Internet Explorer from PHP when script is loaded from another domain

Question

Ok, this is a little complicated:

1. I set a cookie on domain foo.com with php:

   header('P3P:CP="IDC DSP COR ADM DEVi TAIi PSA PSD IVAi IVDi CONi HIS OUR IND CNT"'); setcookie("c", "value", strtotime( '+30 days' ));

2. I call the script <script src='http://foo.com/script.php'> from domain bar.com that loads a javascript file that is output through php

   header('Content-Type: application/javascript');
echo $_COOKIE['c'];

Now, when I open http://foo.com/script.php in Chrome, Firefox, Edge or Internet Explorer, it will display value .
When I instead load the script from bar.com , it will also display value in Chrome, Edge(!) and Firefox, but in the Internet Explorer 10/11, the cookie is not set and cannot be read.

I do not understand why the cookie is not set in IE since I am loading the script from foo.com where the cookie was set initially. So, the script should have access to the cookie.

Any ideas highly appreciated.

Answer 1

What local domain names are you using to call these scripts?

I remember that IE is sometimes peculiar about domain names it accepts cookies for, they need to contain at least one dot . – names such a localhost tend to cause problems in that regard.