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.

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

According to data from Shodan, a search engine that helps to identify internet-linked equipment, over 8,000 servers online could theoretically have already been compromised by hackers.

Unknown attackers exploited a vulnerability in Microsoft’s SharePoint collaboration software, hitting targets around the world.

Hackers exploited a zero-day vulnerability in Microsoft SharePoint servers, targeting US federal agencies and other entities.