CVE-2021-40444: Microsoft MSHTML Remote Code Execution Vulnerability

CVE-2021-40444 · Severity: critical · CVSS 8.8 · Exploited in the wild · Published 2021-11-03

A remote code execution vulnerability exists in the Microsoft MSHTML browser engine when processing specially crafted Microsoft Office documents. An attacker can exploit this by tricking a user into opening a malicious document containing a crafted ActiveX control, potentially leading to full system compromise depending on user permissions.

Technologies: Microsoft Mshtml. Vendors: Microsoft.

Quick answers

Is CVE-2021-40444 exploited in the wild?
Yes. CVE-2021-40444 is known to be exploited in the wild, first recorded on 3 November 2021. Treat it as urgent.
How severe is CVE-2021-40444?
Critical severity, with a CVSS score of 8.8, published 3 November 2021.
Which products and versions are affected?
Microsoft Windows 10 20H2, 21H1, 1607, 1809, 1909, 2004; Microsoft Windows 7 SP1; Microsoft Windows 8.1; Microsoft Windows RT 8.1; and 2 more.
Is there a fix for CVE-2021-40444?
A patch was published on 2021-09-14: Microsoft released security updates to address the vulnerability. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2021-40444 attacked?
It is attacked over the network, in an operating system.
Am I affected by CVE-2021-40444?
Check whether you run Microsoft Mshtml. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

Affected products

  • Microsoft Windows 10 20H2, 21H1, 1607, 1809, 1909, 2004
  • Microsoft Windows 7 SP1
  • Microsoft Windows 8.1
  • Microsoft Windows RT 8.1
  • Microsoft Windows Server 2008 SP2, R2 SP1
  • Microsoft MSHTML

Timeline

  • 2021-09-14: patched: Microsoft released security updates to address the vulnerability.
  • 2021-11-03: disclosed: Initial publication date.
  • 2021-11-03: kev added: Added to CISA Known Exploited Vulnerabilities Catalog.
  • exploited: Microsoft reported awareness of targeted attacks using specially-crafted Office documents.

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