Is a memory error actually an exploit? If so then are the unwanted changes that occur with no deliberate action an example of the computer cracking itself? Philosophical...
I think there is a useful distinction between a fault/error and an exploit. A fault is a break from the "desired" or "expected" semantics of a system, while an exploit is an algorithm to predictably utilize a fault (or faults) to access unexpected behaviours in that system. I.e., a buffer overflow is a fault in a program (breaking the expectation that a buffer's contents will remain within a certain bound), while an exploit targeting that overflow will likely allow running arbitrary code in a program not designed to do so.
So, I'd put it, the memory error can be leveraged in an exploit.