New user have all privilege in MySQL 5.6

New user have all privilege in MySQL 5.6

I have a problem when I create a new user in mySQL 5.6
What I want : When i create the new user, he doesn't have any privilege,
and I just want to grant some select and update in few column. So he can't
the and update all the DB. Sounds fair.
so, first, i create a new user :
CREATE USER 'newuser'@'%' IDENTIFIED BY 'password';
After this, i log in with my new user and when i do a show grants; command
I have this :
GRANT USAGE ON *.* TO 'newuser'@'%' IDENTIFIED BY PASSWORD
'*2470C0C06DEE42FD1618BB99005ADCA2EC9D1E19'
So in my theory he cant do anything in my database bacause he don't have
any GRANT SELECT privilege.
But when i do a Select in my test table he can view all column and all
result. He can update ... Do everything he want to. It's like he have a
GRANT SELECT,UPDATE,DELETE ... ON *.* TO 'newuser'@'%' but I can't revoke
that because he don't have that...
Of course I try to revoke all privileges, but i can't because he dont have
any privileges...
I hope i'm clear. So i'm confused, any idea ?
Thanks
Clément