New Delhi, July 22 -- Microsoft has issued an emergency fix to close off a vulnerability in Microsoft's widely-used SharePoint software that hackers have exploited to carry out widespread attacks on businesses and at least some U.S. government agencies.

The company issued an alert to customers Saturday saying it was aware of the zero-day exploit being used to conduct attacks and that it was working to patch the issue. Microsoft updated its guidance Sunday with instructions to fix the problem for SharePoint Server 2019 and SharePoint Server Subscription Edition. Engineers were still working on a fix for the older SharePoint Server 2016 software.

"Anybody who's got a hosted SharePoint server has got a problem," said Adam Meyers, senior vi...