A global cyberattack exploiting a zero-day flaw in Microsoft SharePoint servers has compromised thousands of organizations, prompting urgent security updates and coordinated federal response.

The US agency overseeing nuclear weapons breached in a China-linked hack of Microsoft SharePoint, according to Bloomberg. Officials say no classified data was exposed and the impact was limited.

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

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

A massive cyber-espionage campaign has compromised nearly 400 organizations globally by exploiting a critical vulnerability in Microsoft SharePoint servers. Eye Security researchers discovered the ongoing attacks,