Remote code execution in Microsoft MSHTML

Published: 2021-09-07 | Updated: 2021-09-14
Risk Critical
Patch available YES
Number of vulnerabilities 1
CVE-ID CVE-2021-40444
Exploitation vector Network
Public exploit This vulnerability is being exploited in the wild.
Vulnerable software
Operating systems & Components / Operating system

Windows Server
Operating systems & Components / Operating system

Microsoft Internet Explorer
Client/Desktop applications / Web browsers

Vendor Microsoft

Security Bulletin

This security bulletin contains information about 1 vulnerabilities.

Updated: 14.09.2021

Changed bulletin status to patched.

1) Code Injection

EUVDB-ID: #VU56377

Risk: Critical


CVE-ID: CVE-2021-40444

CWE-ID: CWE-94 - Improper Control of Generation of Code ('Code Injection')

Exploit availability: Yes


The vulnerability allows a remote attacker to execute arbitrary code on the target system.

The vulnerability exists due to improper input validation within the MSHTML component. A remote attacker can create a specially crafted Office document with a malicious ActiveX control inside, trick the victim into opening the document and execute arbitrary code on the system.

Successful exploitation of this vulnerability may result in complete compromise of vulnerable system.

Note, the vulnerability is being actively exploited in the wild.


Install update from vendor's website.

Vulnerable software versions

Windows: 8.1 - 10 S

Windows Server: 2008 - 2019 2004

Microsoft Internet Explorer: 11

CPE2.3 External links

Q & A

Can this vulnerability be exploited remotely?

Is there known malware, which exploits this vulnerability?