If exploited, attackers can gain full access to SharePoint content and potentially pivot to Outlook, Teams, and OneDrive. Learn how to protect your SharePoint server from compromise.

Security researchers say Microsoft customers should take immediate action to defend against the ongoing cyberattacks, and must assume they have already been compromised.

Hackers have exploited vulnerabilities in Microsoft’s SharePoint software, placing tens of thousands of on-premises servers used by global businesses and agencies at risk. Microsoft issued an alert on Saturday disclosing that it was aware of “active attacks,” and that it was working to patch the zero-day exploit.