CVE-2021-33742: Microsoft Windows MSHTML Platform Remote Code Execution Vulnerability

CVE-2021-33742 · Severity: critical · CVSS 8.8 · Exploited in the wild · Published 2021-11-03

Microsoft Windows MSHTML Platform contains an out-of-bounds write vulnerability (CWE-787) that allows for remote code execution. The vulnerability is triggered when a user visits a specially crafted website or opens a malicious file, leading to memory corruption.

Technologies: Microsoft Windows. Vendors: Microsoft.

Quick answers

Is CVE-2021-33742 exploited in the wild?
Yes. CVE-2021-33742 is known to be exploited in the wild, first recorded on 3 November 2021. Treat it as urgent.
How severe is CVE-2021-33742?
Critical severity, with a CVSS score of 8.8, published 3 November 2021.
Which products and versions are affected?
Microsoft Windows 10 1507, 1607, 1809, 1909, 2004, 20H2, 21H1; Microsoft Windows 7 SP1; Microsoft Windows 8.1; Microsoft Windows RT 8.1; and 4 more.
Is there a fix for CVE-2021-33742?
No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
How is CVE-2021-33742 attacked?
It is attacked over the network, in an operating system.
Am I affected by CVE-2021-33742?
Check whether you run Microsoft Windows. 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 1507, 1607, 1809, 1909, 2004, 20H2, 21H1
  • Microsoft Windows 7 SP1
  • Microsoft Windows 8.1
  • Microsoft Windows RT 8.1
  • Microsoft Windows Server 2008 R2 SP1, SP2
  • Microsoft Windows Server 2012 R2
  • Microsoft Windows Server 2016 2004, 20H2, 1909
  • Microsoft Windows Server 2019

Timeline

  • 2021-06-14: disclosed: Initial analysis by NIST
  • 2021-11-03: kev added: Added to CISA Known Exploited Vulnerabilities Catalog
  • 2021-11-03: advisory: Published date listed in advisory
  • 2021-11-03: exploited: Reported as exploited in the wild in CISA KEV catalog

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