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.

The term "zero-day" attack refers to when a previously unknown vulnerability is targeted. Tens of thousands of servers are said to be at risk. While the issue is serious, it differs from several previous vulnerabilities related to Microsoft. The attack only affects on-premises servers; cloud-based servers are unaffected.

Microsoft is issuing an emergency fix to close off a vulnerability in Microsoft’s SharePoint software that hackers have exploited to carry out widespread attacks on businesses and at least some federal agencies.