Richard Ledgett -- a former Deputy Director of the NSA -- argues against the US government disclosing all vulnerabilities:
Proponents argue that this would allow patches to be developed, which in turn would help ensure that networks are secure. On its face, this argument might seem to make sense -- but it is a gross oversimplification of the problem, one that not only would not have the desired effect but that also would be dangerous.
Actually, he doesn't make that argument at all. He basically says that security is a lot more complicated than finding and disclosing vulnerabilities -- something I don't think anyone disagrees with. His conclusion:
Malicious software like WannaCry and Petya is a scourge in our digital lives, and we need to take concerted action to protect ourselves. That action must be grounded in an accurate understanding of how the vulnerability ecosystem works. Software vendors need to continue working to build better software and to provide patching support for software deployed in critical infrastructure. Customers need to budget and plan for upgrades as part of the going-in cost of IT, or for compensatory measures when upgrades are impossible. Those who discover vulnerabilities need to responsibly disclose them or, if they are retained for national security purposes, adequately safeguard them. And the partnership of intelligence, law enforcement and industry needs to work together to identify and disrupt actors who use these vulnerabilities for their criminal and destructive ends. No single set of actions will solve the problem; we must work together to protect ourselves. As for blame, we should place it where it really lies: on the criminals who intentionally and maliciously assembled this destructive ransomware and released it on the world.
I don't think anyone would argue with any of that, either. The question is whether the US government should prioritize attack over defense, and security over surveillance. Disclosing, especially in a world where the secrecy of zero-day vulnerabilities is so fragile, greatly improves the security of our critical systems.
from More on the Vulnerabilities Equities Process