Steps to reproduce

1. Create clean install of Experience 4.6.x-dev with Varnish reverse proxy.
2. Log in to the back-office (admin).
3. Go to dashboard page
4. Create another admin user
5. Log in to that user
6. Go to dashboard page.

Actual result

Observe that dashboard page serves user widget in the top right corner using previously cached output. Can be compared with what you get when viewing some other admin page (Content structure, user settings, etc.)

Expected result

Cached is correctly served or invalidated. Technically cache will be disabled for the dashboard view as it makes the most sense ATM in general.