A new revision of the installers, virtual machines and cloud images of CiviCRM was just released and they include the latest version of Drupal 7.
If you want to update the version of Drupal in your actual installation you can run the following commands:
You will get an output like this one
Update information last refreshed: Wed, 04/06/2016 - 08:57
Name Installed Version Proposed version Message
Drupal 7.41 7.43 SECURITY UPDATE available
I hope it helps.