Ah, yes. To blame someone, we must first invent the universe.

Sure, SolarWinds is a corporation, it will have a Board of Directors representing the interests of its shareholders, it has at times been a private company (so its shareholders were some handful of private equity investment companies) and public (so they will have included funds and the great unwashed) but in either case the Directors are responsible.

So in terms of specific people that's Bill Bock, the chairman of that board at the time.

They did indeed replace their CEO. I would assume after agreeing to pay off the old one as this is the usual practice and, unlike some no-name intern, a handsomely compensated CEO can afford expensive lawyers if you try to kick them out uncompensated for incompetence based merely on the evidence that their inadequate oversight cost you billions of dollars.