[gambiting]

There are actually 3 different OSes running on the Xbox One. Applications are in their own OS, so any "kernel" exploit would only grant them access to that very limited OS that can't run games. Unless, of course, they somehow manage to escape that container and force VM to run their own modified version of GameOS.

[my123]

A modified version of Hyper-V called NanoVisor is used. Apps run in SystemOS, which is already accessible officially even through other ways... GameOS and HostOS use a stripped-down version of the NT kernel, compiled differently and without binary compat.

[TazeTSchnitzel]

Yes, can't anyone make a Windows Store app for Xbox One?

[my123]

Anyone can, that's right ;) Every Windows Store(UWP) app that isn't a game* is automatically pushed to Xbox devices also, except if the developer opts out.

* for games, it's separately handled for validation