Source? We know that governments and secret services hoard exploits (from the Snowden leaks). But we should remain precise about what we know they had access t

Source? We know that governments and secret services hoard exploits (from the Snowden leaks). But we should remain precise about what we know they had access to and what not, e.g. to investigate possible past breaches. But saying 'this was an exploit that was possibly use by a government' without any proof does not contribute to the debate.