CiviMail - KCFinder upload issues - "You must be logged in with proper permissions", Chrome only
I had the same problem in civicrm 4.6 drupal 7.50.

I made this patch to fix the issue, i hope that will be useful.
https://github.com/rubofvil/civicrm-packages/commit/563a422384ae20cc0077225bebb748813fa6b22d.patch