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.

Microsoft is investigating a potential leak within its MAPP program, suspecting that Chinese state-backed hackers exploited SharePoint vulnerabilities before patches were widely available. The security flaw,

Microsoft confirms Chinese hackers exploited a SharePoint flaw; Patches now available. Cloud-based Microsoft 365 not affected.