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

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.

In an alert issued on Saturday, Microsoft said the vulnerabilities apply only to SharePoint servers used within organizations. It said that SharePoint Online in Microsoft 365, which is in the cloud, was not hit by the attacks.