The patches fix the security holes in more recent versions of SharePoint, but the 2016 version is still at risk.

State CISOs in North Carolina and Arizona said their teams began work immediately to ensure on-prem SharePoint systems were secure, following the recent disclosure of an active zero-day exploit.

Dubbed a “zero-day” because it leverages a previously undisclosed digital weakness, the hacks allow spies to penetrate vulnerable servers and potentially drop a backdoor to secure continuous access to victim organisations.

A major cyberespionage operation targeting Microsoft's SharePoint server software has compromised about 100 organizations worldwide. The operation exploits a zero-day vulnerability, allowing hackers to install backdoors on affected servers.