Several changes were applied to improve security. See ADV-2017-11 through ADV-2017-15 in Security Bulletins for more details.
Ons, 21 Juni, 2017
Release Notes for Tableau 8.3.20
Note: Tableau Desktop customers in environments with Product Updates enabled will be prompted to upgrade a few days after a maintenance release is made available. For more information, see the Tableau Knowledge Base.