The following bug has been logged on the website:
Bug reference: 14828
Logged by: Randy Grolemund
Email address: randygrolemund(at)gmail(dot)com
PostgreSQL version: 9.6.5
Operating system: Linux
Description:
Another team member created a new db, and did not assign any users
permission to that db. It appears at least one of the users (no super user
permissions) can read and write to that db. It doesn't make any sense how
this is working.