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

Source: https://junglewise.ai/threats/cve-2021-33771-microsoft-windows-kernel-privilege-escalation-vulnerability  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2021-11-03. Updated: 2026-05-10  
License: CC BY 4.0 with a link back

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](https://junglewise.ai/threats/technologies/windows). Vendors: [Microsoft](https://junglewise.ai/threats/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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