How severe is CVE-2021-33771?

CVE-2021-33771 has a CVSS 3.1 base score of 7.8 (HIGH). EPSS estimates a 10.2% probability of exploitation in the next 30 days. It is listed in the CISA Known Exploited Vulnerabilities catalog.

CVE-2021-33771: Windows Kernel Elevation of Privilege

CISA Known Exploited Vulnerabilities

Microsoft Windows Kernel Privilege Escalation Vulnerability is confirmed as actively exploited and is listed in the CISA KEV catalog.

Added to KEV

2021-11-03

Remediation due

2021-11-17

Required action
Apply updates per vendor instructions.

CISA notes
https://nvd.nist.gov/vuln/detail/CVE-2021-33771

Description

Windows Kernel Elevation of Privilege Vulnerability

Severity

CVSS 3.1 · CNA7.8 HIGH

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:F/RL:O/RC:C

SSVC · CISA-ADP

Exploitationactive

Automatableno

Technical impacttotal

Affected Products

Vendor	Product	Affected versions
Microsoft	Windows 10 Version 1507	10.0.10240.0 to <10.0.10240.19003
Microsoft	Windows 10 Version 1607	10.0.14393.0 to <10.0.14393.4530
Microsoft	Windows 10 Version 1809	10.0.17763.0 to <10.0.17763.2061
Microsoft	Windows 10 Version 1809	10.0.0 to <10.0.17763.2061
Microsoft	Windows 10 Version 1909	10.0.0 to <10.0.18363.1679
Microsoft	Windows 10 Version 2004	10.0.0 to <10.0.19041.1110
Microsoft	Windows 10 Version 20H2	10.0.0 to <10.0.19042.1110
Microsoft	Windows 10 Version 21H1	10.0.0 to <10.0.19043.1110
Microsoft	Windows 8.1	6.3.0 to <6.3.9600.20069
Microsoft	Windows Server 2012 R2	6.3.9600.0 to <6.3.9600.20069
Microsoft	Windows Server 2012 R2 (Server Core installation)	6.3.9600.0 to <6.3.9600.20069
Microsoft	Windows Server 2016	10.0.14393.0 to <10.0.14393.4530
Microsoft	Windows Server 2016 (Server Core installation)	10.0.14393.0 to <10.0.14393.4530
Microsoft	Windows Server 2019	10.0.17763.0 to <10.0.17763.2061
Microsoft	Windows Server 2019 (Server Core installation)	10.0.17763.0 to <10.0.17763.2061
Microsoft	Windows Server version 2004	10.0.0 to <10.0.19041.1110
Microsoft	Windows Server version 20H2	10.0.0 to <10.0.19042.1110

References

2 Links

Vendor advisories

Windows Kernel Elevation of Privilege Vulnerability

Other references

https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-33771

Record Details

Published

2021-07-14

Last updated

2026-08-10

Assigner (CNA)

microsoft

Credited to

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CVE record data © The MITRE Corporation, used under the CVE Terms of Use. Exploited-in-the-wild data from the CISA Known Exploited Vulnerabilities catalog (CC0). Exploit prediction scores by FIRST EPSS (first.org/epss). This site is not endorsed or certified by MITRE, NVD, CISA, or FIRST.