Hi Henri GILABERT,

Sorry for late reply to this,

Actually that was not call hacking. I believe that was your current Easyblog ACL setting allow registered user have permission to submit a blog post.

To fix this, you can disable this write/publish entry permission from your backend > Easyblog > ACL > Registered user group > Check my screenshot below.

If you would like temporary disable your site user registration, you can go to disable from your backend > User > user manager > option > allow user registration - NO

Hope this help.