Comment 1 for bug 1735929

Hell User2233, this is an intentional design choice to enable users to share with each other. If this isn't appropriate for your environment you can modify the DIR_MODE variable in /etc/adduser.conf to set the permissions as desired.

https://help.ubuntu.com/lts/serverguide/user-management.html#user-profile-security

Thanks for reporting this issue, don't hesitate to report future issues.