Microsoft zeroday MSHTML vulnerability

This blog contains information about the Microsoft zeroday MSHTML (CVE-2021-40444) vulnerability. As soon as we have an update, we’ll add it to this post. More information about possible risks and details can be found at the bottom of this blog.

Update September 9, 2021

17:00 | On September 7, a vulnerability was revealed in MSHTML that could allow the attacker to execute code remotely. This concerns the ActiveX control.

An attacker could create a malicious ActiveX control that could be used by a Microsoft Office application 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 may be less affected than users in Administrator/Administrator status.

Microsoft Defender Antivirus and Microsoft Defender for Endpoint both provide detection and protection for this vulnerability. Customers using automatic updates do not need to take any additional action.

Disabling the installation of all ActiveX controls in Internet Explorer mitigates this attack.

‍