At least three China-based hacking teams have been exploiting a previously unknown flaw in Microsoft SharePoint since at least July 7, the company said in a blog post. Why it matters: Microsoft and security researchers didn't uncover the vulnerability until this past weekend,

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