Microsoft today published an advisory with a workaround to mitigate an unpatched vulnerability in Microsoft Office. This vulnerability is currently used in targeted attacks.

CVE-2021-40444 is a code execution vulnerability in MSHTML. The exploit would arrive as an Office document that includes a malicious ActiveX control. As a workaround, Microsoft recommends disabling ActiveX in Internet Explorer and the advisory includes the necessary registry changes. At this point, it should be pretty low impact to disable ActiveX, but of course, there may be individual enterprise applications that still use ActiveX. 

For more details, see Microsoft's advisory here: 

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-40444

---
Johannes B. Ullrich, Ph.D. , Dean of Research, SANS.edu
Twitter|