I have a CORS (cross origin resource sharing) request coming from my login page to the application site, on a different URL. I have a simple page I ping to determine if a us
Found the issue.
I had a similar problem (using CORS in general, not specifically GWT). It turned out that the browser settings were blocking third-party cookies (IE10 > Internet Options > Privacy > Advanced > Third Party Cookies > Accept). To solve the problem, I checked "Override automatic cookie handling", "Accept" (Third-party Cookies) and "Always allow session cookies."
Andrew answered this question here: CORS doesn't work with cookies in IE10
EDIT: (Now that I know what to search for) This question may yield some help too, if anyone else runs into this issue. Internet Explorer 10 is ignoring XMLHttpRequest 'xhr.withCredentials = true'