There are probably loads of exploitable bugs within the 4.0/4.0.1/4.1.0 kernel and firmware versions, but remember: just because they haven't been discovered yet does not mean there aren't any.
In fact, it is literally impossible to write a piece of software which is completely bug-free! Human error, loopholes and zero-day hardware faults are just some of the factors which attribute to bugs.
I guarantee, with 100% certainty, that within the next 6 months or so an exploit for 4.1.0 will be found.
TL;DR:
Nintendo aren't perfect; their team isn't perfect, bugs will always be there; they're just waiting to be found.