As per the recent post on the Microsoft Security Response Center, dated September 9, 2021, Microsoft has released an alert about a serious vulnerability in MSHTML. MSHTML is a component in Internet Explorer and in Microsoft Office used to render web content. No known patch has been released, but there are mitigating steps that can be followed.
We advise you follow Microsoft’s recommendation to keep your antivirus software up to date. Additionally, we recommend you only open Microsoft Office documents created by a trusted source, not use Internet Explorer for browsing web pages, and keep an eye out for future Microsoft Windows and Office update that address this issue.
For information on how to update your antivirus software, see your antivirus vendors web site. If you are using Internet Explorer to browse web pages, please discontinue use. Internet Explorer is scheduled for end of support by Microsoft as per the Microsoft Support page, Internet Explorer 11 to be retired. If you use web applications that require Internet Explorer, contact the web application vendor to determine their recommendations.