It is though. Unless some modder in the world has some private modification to his console that literally nobody else knows about or knows how to do, you can pretty much be 99% sure there are no mods or hacking like this going on.

Anything is possible, because exploits within systems can be found at any moment, but it hasn’t happened yet in it’s entire life cycle, it’s so unlikely that it’s not unreasonable to say it’s out of the question. Any exploits that have been found are minimal and don’t amount to any actual modding being done. If an exploit is found at some point that enables you to mod say, game files, etc. , it will probably be awhile, and very very few people will have it anyways.

EDIT. Just want to point out I’m talking about Xbone/Ps4 and up for anyone wondering. Ps3 and 360 consoles were hacked pretty much from the beginning of there release.