How severe is CVE-2021-31956?

CVE-2021-31956 has a CVSS 3.1 base score of 7.8 (HIGH). EPSS estimates a 22.3% probability of exploitation in the next 30 days. It is listed in the CISA Known Exploited Vulnerabilities catalog.

CVE-2021-31956: Windows NTFS Elevation of Privilege Vulnerability

CISA Known Exploited Vulnerabilities

Microsoft Windows NTFS 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-2021-31956

Description

Windows NTFS 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

Exploitation Context

as of October 14, 2026

All KEV statistics→

CISA added CVE-2021-31956 to the KEV catalog 148 days after its CVE record was published.
It is one of 391 Microsoft entries in the CISA KEV catalog, and one of 83 added in 2021.
Its current EPSS score (22.3%) is higher than that of 36% of CISA KEV entries.

Affected Products

Vendor	Product	Affected versions
Microsoft	Microsoft Windows 10 Version 1809	10.0.0 to <10.0.17763.1999
Microsoft	Microsoft Windows Server 2019	10.0.0 to <10.0.17763.1999
Microsoft	Microsoft Windows Server 2019 (Server Core installation)	10.0.0 to <10.0.17763.1999
Microsoft	Microsoft Windows 10 Version 1909	10.0.0 to <10.0.18363.1621
Microsoft	Microsoft Windows 10 Version 21H1	10.0.0 to <10.0.19043.1052
Microsoft	Microsoft Windows 10 Version 2004	10.0.0 to <10.0.19041.1052
Microsoft	Microsoft Windows Server version 2004	10.0.0 to <10.0.19041.1052
Microsoft	Microsoft Windows 10 Version 20H2	10.0.0 to <10.0.19042.1052
Microsoft	Microsoft Windows Server version 20H2	10.0.0 to <10.0.19042.1052
Microsoft	Microsoft Windows 10 Version 1507	10.0.0 to <10.0.10240.18967
Microsoft	Microsoft Windows 10 Version 1607	10.0.0 to <10.0.14393.4467
Microsoft	Microsoft Windows Server 2016	10.0.0 to <10.0.14393.4467
Microsoft	Microsoft Windows Server 2016 (Server Core installation)	10.0.0 to <10.0.14393.4467
Microsoft	Microsoft Windows 7	6.1.0 to <6.1.7601.25632
Microsoft	Microsoft Windows 7 Service Pack 1	6.1.0 to <6.1.7601.25632
Microsoft	Microsoft Windows 8.1	6.3.0 to <6.3.9600.20045 6.3.0 to <6.3.9600.20044
Microsoft	Microsoft Windows Server 2008 Service Pack 2	6.0.0 to <6.0.6003.21137
Microsoft	Microsoft Windows Server 2008 Service Pack 2 (Server Core installation)	6.0.0 to <6.0.6003.21137
Microsoft	Microsoft Windows Server 2008 Service Pack 2	6.0.0 to <6.0.6003.21137
Microsoft	Microsoft Windows Server 2008 R2 Service Pack 1	6.1.0 to <6.1.7601.25632
Microsoft	Microsoft Windows Server 2008 R2 Service Pack 1 (Server Core installation)	6.0.0 to <6.1.7601.25632
Microsoft	Microsoft Windows Server 2012	6.2.0 to <6.2.9200.23372
Microsoft	Microsoft Windows Server 2012 (Server Core installation)	6.2.0 to <6.2.9200.23372
Microsoft	Microsoft Windows Server 2012 R2	6.3.0 to <6.3.9600.20045 6.3.0 to <6.3.9600.20044
Microsoft	Microsoft Windows Server 2012 R2 (Server Core installation)	6.3.0 to <6.3.9600.20045 6.3.0 to <6.3.9600.20044

References

1 Links

Other references

https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-31956

Record Details

Published

2021-06-08

Last updated

2026-01-12

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.