For the past few weeks companies have been struggling to cope with an easily exploited vulnerability in the MSHTML Internet Explorer browser rendering engine which was being used by hackers in phishing campaigns to hack company networks.
Described in CVE-2021-40444, Microsoft notes:
An attacker could craft a malicious ActiveX control to be used by a Microsoft Office document that hosts the browser rendering engine. The attacker would then have to convince the user to open the malicious document. Users whose accounts are configured to have fewer user rights on the system could be less impacted than users who operate with administrative user rights.
The hack had a severity of 8.8/10 and hackers were able to bypass the mitigations Microsoft suggested.
Today Microsoft announced that they have released a fix for the exploit as part of Patch Tuesday, saying:
September 14, 2021: Microsoft has released security updates to address this vulnerability. Please see the Security Updates table for the applicable update for your system. We recommend that you install these updates immediately.
The fix is being delivered via the Monthly Security Rollup for Windows 7, Windows Server 2008 R2, and Windows Server 2008. Windows 10 users can check for updates in Settings.