"I think it's readily known that Microsoft has numerous zero-days (discovered or not) in their software."
This is true for every single piece of software ever written. Msft is no different in this regard.
This is true for every single piece of software ever written. Msft is no different in this regard.
Then there's also Coq and such.
Of course, usually the amount of vulnerabilities exponentially correlates to the size of the codebase.