Hackers in recent weeks have exploited flaws in SharePoint, a document management system developed by Microsoft Corp., to try to steal sensitive data from hundreds of victims.

Microsoft confirmed “active” cyberattacks exploiting vulnerabilities in on-premises SharePoint Servers and released emergency patches for several versions of the systems.

Victims of the recent global hacking campaign include the National Institutes of Health and the National Nuclear Security Administration, officials said.

Microsoft has released security updates addressing the exploited vulnerabilities and urged all customers to apply patches without delay.

Microsoft has issued a high-priority security alert over ongoing cyberattacks targeting its SharePoint server software. The company urged affected users to apply critical security updates

Hackers have already compromised more than 400 organizations using a recently discovered flaw in Microsoft SharePoint servers, according to researchers at Eye Security. Why it matters: That number has raised dramatically from estimates earlier this week that hackers had only broke into about 60 government agencies,