Sure there is a legitimate reason to withhold them, though many would say it's not a very ethical one: money. Private researchers hold them for sale to the NSA

Sure there is a legitimate reason to withhold them, though many would say it's not a very ethical one: money. Private researchers hold them for sale to the NSA and other agencies all the time. Here are a few exchanges (there are also high end "agents" - akin to Hollywood agents - that broker these deals): [1] https://zerodium.com/ https://zerodium.com/ [2] https://www.mitnicksecurity.com/shopping/absolute-zero-day-exploit-exchange https://www.mitnicksecurity.com/shopping/absolute-zero-day-e... And some info on this market: https://en.wikipedia.org/wiki/Market_for_zero-day_exploits https://en.wikipedia.org/wiki/Market_for_zero-day_exploits