Microsoft has issued 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 major security vulnerability in Microsoft's widely used Sharepoint server software has been exploited by hackers, causing chaos within businesses and government agencies.

Microsoft has warned of “active attacks” targeting its SharePoint collaboration software, with security researchers noting that organizations worldwide stand to be affected by the breach.