CVEs / CVE-2021-36955
CVE-2021-36955: Microsoft Windows Common Log File System (CLFS) Driver Privilege Escalation Vulnerability
- Known exploited in the CISA KEV catalog since 3 Nov 2021
- medium 4.6 CVSS 2.0 (NVD)
- EPSS 4.07% chance of exploitation in the next 30 days, higher than 90% of CVEs (30 Oct 2026)
- Last changed at its sources
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Summary
Microsoft Windows Common Log File System (CLFS) driver contains an unspecified vulnerability that allows for privilege escalation.
Description
Windows Common Log File System Driver Elevation of Privilege Vulnerability
Affected and fixed versions
| Product | Affected | Fixed in |
|---|---|---|
| Microsoft Windows 10 Version 1507 | from 10.0.10240.0, before 10.0.10240.19060 | 10.0.10240.19060 |
| Microsoft Windows 10 Version 1607 | from 10.0.14393.0, before 10.0.14393.4651 | 10.0.14393.4651 |
| Microsoft Windows 10 Version 1809 | from 10.0.17763.0, before 10.0.17763.2183 | 10.0.17763.2183 |
| Microsoft Windows 10 Version 1809 | from 10.0.0, before 10.0.17763.2183 | 10.0.17763.2183 |
| Microsoft Windows 10 Version 1909 | from 10.0.0, before 10.0.18363.1801 | 10.0.18363.1801 |
| Microsoft Windows 10 Version 2004 | from 10.0.0, before 10.0.19041.1237 | 10.0.19041.1237 |
| Microsoft Windows 10 Version 20H2 | from 10.0.0, before 10.0.19042.1237 | 10.0.19042.1237 |
| Microsoft Windows 10 Version 21H1 | from 10.0.0, before 10.0.19043.1237 | 10.0.19043.1237 |
| Microsoft Windows 7 | from 6.1.0, before 6.1.7601.25712 | 6.1.7601.25712 |
| Microsoft Windows 7 Service Pack 1 | from 6.1.0, before 6.1.7601.25712 | 6.1.7601.25712 |
| Microsoft Windows 8.1 | from 6.3.0, before 6.3.9600.20120 | 6.3.9600.20120 |
| Microsoft Windows Server 2008 R2 Service Pack 1 | from 6.1.7601.0, before 6.1.7601.25712 | 6.1.7601.25712 |
| Microsoft Windows Server 2008 R2 Service Pack 1 (Server Core installation) | from 6.1.7601.0, before 6.1.7601.25712 | 6.1.7601.25712 |
| Microsoft Windows Server 2008 Service Pack 2 | from 6.0.6003.0, before 6.0.6003.21218 | 6.0.6003.21218 |
| Microsoft Windows Server 2008 Service Pack 2 (Server Core installation) | from 6.0.6003.0, before 6.0.6003.21218 | 6.0.6003.21218 |
| Microsoft Windows Server 2012 | from 6.2.9200.0, before 6.2.9200.23462 | 6.2.9200.23462 |
| Microsoft Windows Server 2012 (Server Core installation) | from 6.2.9200.0, before 6.2.9200.23462 | 6.2.9200.23462 |
| Microsoft Windows Server 2012 R2 | from 6.3.9600.0, before 6.3.9600.20120 | 6.3.9600.20120 |
| Microsoft Windows Server 2012 R2 (Server Core installation) | from 6.3.9600.0, before 6.3.9600.20120 | 6.3.9600.20120 |
| Microsoft Windows Server 2016 | from 10.0.14393.0, before 10.0.14393.4651 | 10.0.14393.4651 |
| Microsoft Windows Server 2016 (Server Core installation) | from 10.0.14393.0, before 10.0.14393.4651 | 10.0.14393.4651 |
| Microsoft Windows Server 2019 | from 10.0.17763.0, before 10.0.17763.2183 | 10.0.17763.2183 |
| Microsoft Windows Server 2019 (Server Core installation) | from 10.0.17763.0, before 10.0.17763.2183 | 10.0.17763.2183 |
| Microsoft Windows Server 2022 | from 10.0.20348.0, before 10.0.20348.230 | 10.0.20348.230 |
| Microsoft Windows Server version 2004 | from 10.0.0, before 10.0.19041.1237 | 10.0.19041.1237 |
| Microsoft Windows Server version 20H2 | from 10.0.0, before 10.0.19042.1237 | 10.0.19042.1237 |
Exploitation
| In CISA KEV since | 3 Nov 2021 |
|---|---|
| Due date for US federal agencies | 17 Nov 2021 |
| Used in ransomware campaigns | Known |
| Required action | Apply updates per vendor instructions. |
Severity
| CVSS 2.0 | 4.6 mediumAV:L/AC:L/Au:N/C:P/I:P/A:PScored by NVD |
|---|
References
- CVE-2021-36955 on NVD
- CVE-2021-36955 in the CISA KEV catalog
- https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-36955 Patch, Vendor Advisory
- https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-36955 Patch, Vendor Advisory
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-36955 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.