CKEditor 4.5 filetools, XHR.withCredentials = true,

var editor = CKEDITOR.replace( 'editor1', {
extraPlugins: 'uploadimage,filetools',
imageUploadUrl: 'http://sub.ckeditor.dev/ckfinder/core/connector/php/connector.php?command=QuickUpload&type=Images&responseType=json'
} );

editor.on( 'fileUploadRequest', function( e ) {
var xhr = e.data.fileLoader.xhr;
xhr.withCredentials = true;
} );