[taftster]

I'm not sure that governments actually create them, not prolifically at least. There's been some state actor influence over the years, for sure.

However, exploits that are known (only) by a state actor would most definitely be a closely guarded secret. It's only convenient for a state to release information about an exploit when either it's been made public or it has more consequences for not releasing.

So yes, exactly what you said. It's easier to find the exploits than to create them yourself. By extrapolation, you would have to assume that each state maintains its set of secret exploits, possibly never getting to use them for fear of the other side knowing of their existence. Cat & Mouse, Spy vs Spy for sure.