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.

A security patch released by Microsoft last month failed to fully fix a critical flaw in U.S. tech giant's SharePoint server software that had been identified in May, opening the door to a sweeping global cyber espionage operation.

Microsoft warned users that hackers used a security flaw in its server software to attack government agencies and businesses around the world. The federal government, along with those in Canada and Australia, has launched an investigation into the hack that targeted SharePoint servers, The Washington Post reported.