Drupal 7 CDN whitelist issue
I was doing the wrong practices with Drupal Theme, in CSS whenever I have to use the url() to declare the path, I was using url('sites/all/themes/mytheme/images/bg.png') which is considered as Bad Practice, so I changed that to url(../images/bg.png) and same for Images inside misc folder as url('../../../../misc/configure.png') from CSS and everything is working as expected.

To tell long story in short, don't use absolute url from the root in CSS but use relative paths.