A warning has been issued to Microsoft users detailing a cybersecurity flaw that allowed hackers to access its SharePoint servers, the U.S. Cybersecurity and Infrastructure Security Agency (CISA) announced.

Microsoft issued an emergency fix to close off a vulnerability in its SharePoint software that hackers have exploited to carry out widespread attacks on businesses and at least some federal agencies.The software giant on Saturday said it was aware of "active attacks" that exploited vulnerabilities in the program,

Microsoft said the company has been "coordinating closely with CISA, DOD Cyber Defense Command, and key cybersecurity partners around the world throughout our response."

The hackers behind the initial wave of attacks exploiting a zero-day in Microsoft SharePoint servers have so far primarily targeted government organizations, according to researchers as well as news reports.

Microsoft Corp.’s server software is under attack from unidentified hackers, with cybersecurity analysts warning of widespread security breaches across the globe.The Redmond, Washington-based software maker said it had released a new security patch for customers to apply to their SharePoint servers “to mitigate active attacks targeting on-premises servers,