A critical vulnerability in on-premise SharePoint servers allowed state-backed hackers to breach governments and institutions worldwide. Experts are questioning why more hasn't been done or said.

Microsoft is issuing an emergency fix to close off a vulnerability in Microsoft’s SharePoint software that hackers have exploited to carry out widespread attacks on businesses and at least some federal agencies.

In ongoing hacks, Microsoft says it has identified two Chinese hacking groups taking advantage of a key software flaw.