Ah, that is a bit scary. I've done that in the past — and these days, depending on the server environment, it might not be as bad. One of the things I like about CageFS is that it even better containerizes everyone so there's even fewer avenues to exploit to get someone else's files.
Hopefully it was just a glitch in the Matrix rather than an exploit. If an exploit, too, they screwed it up since the idea is to use it for something nefarious, not just break it. So they're *bad* hackers, if it was hackers. hehe