CVEs / CVE-2021-31956
CVE-2021-31956: Microsoft Windows NTFS Privilege Escalation Vulnerability
- Known exploited in the CISA KEV catalog since 3 Nov 2021
- high 9.3 CVSS 2.0 (NVD)
- EPSS 22.2% chance of exploitation in the next 30 days, higher than 97% of CVEs (30 Oct 2026)
- Last changed at its sources
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Summary
Microsoft Windows New Technology File System (NTFS) contains an unspecified vulnerability that allows attackers to escalate privileges via a specially crafted application.
Description
Windows NTFS Elevation of Privilege Vulnerability
Affected and fixed versions
| Product | Affected | Fixed in |
|---|---|---|
| Microsoft Windows 10 Version 1809 | from 10.0.0, before 10.0.17763.1999 | 10.0.17763.1999 |
| Microsoft Windows Server 2019 | from 10.0.0, before 10.0.17763.1999 | 10.0.17763.1999 |
| Microsoft Windows Server 2019 (Server Core installation) | from 10.0.0, before 10.0.17763.1999 | 10.0.17763.1999 |
| Microsoft Windows 10 Version 1909 | from 10.0.0, before 10.0.18363.1621 | 10.0.18363.1621 |
| Microsoft Windows 10 Version 21H1 | from 10.0.0, before 10.0.19043.1052 | 10.0.19043.1052 |
| Microsoft Windows 10 Version 2004 | from 10.0.0, before 10.0.19041.1052 | 10.0.19041.1052 |
| Microsoft Windows Server version 2004 | from 10.0.0, before 10.0.19041.1052 | 10.0.19041.1052 |
| Microsoft Windows 10 Version 20H2 | from 10.0.0, before 10.0.19042.1052 | 10.0.19042.1052 |
| Microsoft Windows Server version 20H2 | from 10.0.0, before 10.0.19042.1052 | 10.0.19042.1052 |
| Microsoft Windows 10 Version 1507 | from 10.0.0, before 10.0.10240.18967 | 10.0.10240.18967 |
| Microsoft Windows 10 Version 1607 | from 10.0.0, before 10.0.14393.4467 | 10.0.14393.4467 |
| Microsoft Windows Server 2016 | from 10.0.0, before 10.0.14393.4467 | 10.0.14393.4467 |
| Microsoft Windows Server 2016 (Server Core installation) | from 10.0.0, before 10.0.14393.4467 | 10.0.14393.4467 |
| Microsoft Windows 7 | from 6.1.0, before 6.1.7601.25632 | 6.1.7601.25632 |
| Microsoft Windows 7 Service Pack 1 | from 6.1.0, before 6.1.7601.25632 | 6.1.7601.25632 |
| Microsoft Windows 8.1 | from 6.3.0, before 6.3.9600.20045 | 6.3.9600.20045 |
| Microsoft Windows 8.1 | from 6.3.0, before 6.3.9600.20044 | 6.3.9600.20044 |
| Microsoft Windows Server 2008 Service Pack 2 | from 6.0.0, before 6.0.6003.21137 | 6.0.6003.21137 |
| Microsoft Windows Server 2008 Service Pack 2 (Server Core installation) | from 6.0.0, before 6.0.6003.21137 | 6.0.6003.21137 |
| Microsoft Windows Server 2008 Service Pack 2 | from 6.0.0, before 6.0.6003.21137 | 6.0.6003.21137 |
| Microsoft Windows Server 2008 R2 Service Pack 1 | from 6.1.0, before 6.1.7601.25632 | 6.1.7601.25632 |
| Microsoft Windows Server 2008 R2 Service Pack 1 (Server Core installation) | from 6.0.0, before 6.1.7601.25632 | 6.1.7601.25632 |
| Microsoft Windows Server 2012 | from 6.2.0, before 6.2.9200.23372 | 6.2.9200.23372 |
| Microsoft Windows Server 2012 (Server Core installation) | from 6.2.0, before 6.2.9200.23372 | 6.2.9200.23372 |
| Microsoft Windows Server 2012 R2 | from 6.3.0, before 6.3.9600.20045 | 6.3.9600.20045 |
| Microsoft Windows Server 2012 R2 | from 6.3.0, before 6.3.9600.20044 | 6.3.9600.20044 |
| Microsoft Windows Server 2012 R2 (Server Core installation) | from 6.3.0, before 6.3.9600.20045 | 6.3.9600.20045 |
| Microsoft Windows Server 2012 R2 (Server Core installation) | from 6.3.0, before 6.3.9600.20044 | 6.3.9600.20044 |
Exploitation
| In CISA KEV since | 3 Nov 2021 |
|---|---|
| Due date for US federal agencies | 17 Nov 2021 |
| Used in ransomware campaigns | Unknown |
| Required action | Apply updates per vendor instructions. |
Severity
| CVSS 2.0 | 9.3 highAV:N/AC:M/Au:N/C:C/I:C/A:CScored by NVD |
|---|---|
| Weakness | CWE-191 |
References
- CVE-2021-31956 on NVD
- CVE-2021-31956 in the CISA KEV catalog
- https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-31956 Patch, Vendor Advisory
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-31956 US Government Resource
Sources
Exploitation status from the CISA Known Exploited Vulnerabilities catalog. EPSS scores from FIRST. Descriptions, severity and references from the National Vulnerability Database. Open-source package versions from OSV (CC-BY 4.0). Text is shown as each source states it; Stackurity does not edit it. Check the vendor's advisory before acting.
This product uses data from the NVD API but is not endorsed or certified by the NVD.