CVE-2021-33771: Microsoft Windows Kernel Privilege Escalation Vulnerability

CVE-2021-33771 · Severity: critical · CVSS 7.8 · Exploited in the wild · Published 2021-11-03

A privilege escalation vulnerability exists in the Microsoft Windows Kernel that allows a local attacker to gain elevated permissions. The vulnerability has been observed being exploited in the wild and is included in CISA's Known Exploited Vulnerabilities Catalog.

Technologies: Microsoft Windows. Vendors: Microsoft.

Quick answers

Is CVE-2021-33771 exploited in the wild?
Yes. CVE-2021-33771 is known to be exploited in the wild, first recorded on 3 November 2021. Treat it as urgent.
How severe is CVE-2021-33771?
Critical severity, with a CVSS score of 7.8, published 3 November 2021.
Which products and versions are affected?
Microsoft Windows 10 up to (excluding) 10.0.10240.19003; Microsoft Windows 10 Version 1607 up to (excluding) 10.0.14393.4530; Microsoft Windows 10 Version 1809 up to (excluding) 10.0.17763.2061; Microsoft Windows 10 Version 1909 up to (excluding) 10.0.18363.1679; and 11 more.
Is there a fix for CVE-2021-33771?
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-2021-33771 attacked?
It is attacked with local access, in an operating system.
Am I affected by CVE-2021-33771?
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 up to (excluding) 10.0.10240.19003
  • Microsoft Windows 10 Version 1607 up to (excluding) 10.0.14393.4530
  • Microsoft Windows 10 Version 1809 up to (excluding) 10.0.17763.2061
  • Microsoft Windows 10 Version 1909 up to (excluding) 10.0.18363.1679
  • Microsoft Windows 10 Version 2004 up to (excluding) 10.0.19041.1110
  • Microsoft Windows 10 Version 20H2 up to (excluding) 10.0.19042.1110
  • Microsoft Windows 10 Version 21H1 up to (excluding) 10.0.19043.1110
  • Microsoft Windows 8.1
  • Microsoft Windows RT 8.1
  • Microsoft Windows Server 2004 up to (excluding) 10.0.19041.1110
  • Microsoft Windows Server 2008
  • Microsoft Windows Server 2012 R2
  • Microsoft Windows Server 2016 up to (excluding) 10.0.14393.4530
  • Microsoft Windows Server 2019 up to (excluding) 10.0.17763.2061
  • Microsoft Windows Server 20H2 up to (excluding) 10.0.19042.1110

Timeline

  • 2021-07-16: disclosed: Initial analysis by NIST
  • 2021-11-03: kev added: Added to CISA Known Exploited Vulnerabilities Catalog
  • 2021-11-03: advisory: Published date reported in advisory summary

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