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CVE-2021-40466

25
FAUCET Score

CVE-2021-40466 is an Elevation of Privilege vulnerability in the Windows Common Log File System Driver, affecting numerous Windows operating systems from Windows 7 to Windows 11 and various Windows Server versions. With a CVSS score of 7.8 (High), this vulnerability allows a local attacker with low privileges to achieve high impact on confidentiality, integrity, and availability without user interaction. While not actively exploited in the wild (no KEV entry) and lacking public exploit code in Metasploit or ExploitDB, it has garnered some community discussion and media coverage, indicating awareness within the security community.

Impacted Technologies

VendorProductVersion(s)CPE
Range not provided by sourceCPE matchmatch criteria
cpe:2.3:o:microsoft:windows_10:-:*:*:*:*:*:*:*
20h2CPE matchmatch criteria
cpe:2.3:o:microsoft:windows_10:20h2:*:*:*:*:*:*:*
21h1CPE matchmatch criteria
cpe:2.3:o:microsoft:windows_10:21h1:*:*:*:*:*:*:*
1607CPE matchmatch criteria
cpe:2.3:o:microsoft:windows_10:1607:*:*:*:*:*:*:*
1809CPE matchmatch criteria
cpe:2.3:o:microsoft:windows_10:1809:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

7.8HIGH

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Attack Vector
LOCAL
Attack Complexity
LOW
Privileges Required
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
Exploitability Score
1.8
Impact Score
5.9
CvssVersion
3.1

Exploit Intelligence

EPSS Score
0.64%
Probability of exploitation in next 30 days
EPSS Percentile
46.8%
Percentile rank of EPSS score among Peer Group
As of 2026-07-28
Model: v2026.06.15
This CVE's current EPSS score of 0.0064 is in the 85th percentile among its peer group of 17,070 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.1 Reddit, 0.2 Bluesky, 0.1 Mastodon, and 0.2 GitHub mentions.

Media Mentions

The average CVE in this peer group has 0.3 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (44)

microsoftpatch availablevia nvd_reference
View patch
microsoftpatch availablevia msrc
Product: Windows 10 Version 1809 for 32-bit SystemsFixed in: 10.0.17763.2237
View patch
microsoftpatch availablevia msrc
Product: Windows 10 Version 1809 for x64-based SystemsFixed in: 10.0.17763.2237
View patch
microsoftpatch availablevia msrc
Product: Windows 10 Version 1809 for ARM64-based SystemsFixed in: 10.0.17763.2237
View patch
microsoftpatch availablevia msrc
Product: Windows Server 2019Fixed in: 10.0.17763.2237
View patch
microsoftpatch availablevia msrc
Product: Windows Server 2019 (Server Core installation)Fixed in: 10.0.17763.2237
View patch
microsoftpatch availablevia msrc
Product: Windows 10 Version 1909 for 32-bit SystemsFixed in: 10.0.18363.1854
View patch
microsoftpatch availablevia msrc
Product: Windows 10 Version 1909 for x64-based SystemsFixed in: 10.0.18363.1854
View patch
microsoftpatch availablevia msrc
Product: Windows 10 Version 1909 for ARM64-based SystemsFixed in: 10.0.18363.1854
View patch
microsoftpatch availablevia msrc
Product: Windows 10 Version 21H1 for x64-based SystemsFixed in: 10.0.19043.1288
View patch
microsoftpatch availablevia msrc
Product: Windows 10 Version 21H1 for ARM64-based SystemsFixed in: 10.0.19043.1288
View patch
microsoftpatch availablevia msrc
Product: Windows 10 Version 21H1 for 32-bit SystemsFixed in: 10.0.19043.1288
View patch
microsoftpatch availablevia msrc
Product: Windows Server 2022Fixed in: 10.0.20348.288
View patch
microsoftpatch availablevia msrc
Product: Windows Server 2022 (Server Core installation)Fixed in: 10.0.20348.288
View patch
microsoftpatch availablevia msrc
Product: Windows 10 Version 2004 for 32-bit SystemsFixed in: 10.0.19041.1288
View patch
microsoftpatch availablevia msrc
Product: Windows 10 Version 2004 for ARM64-based SystemsFixed in: 10.0.19041.1288
View patch
microsoftpatch availablevia msrc
Product: Windows 10 Version 2004 for x64-based SystemsFixed in: 10.0.19041.1288
View patch
microsoftpatch availablevia msrc
Product: Windows Server, version 2004 (Server Core installation)Fixed in: 10.0.19041.1288
View patch
microsoftpatch availablevia msrc
Product: Windows 10 Version 20H2 for 32-bit SystemsFixed in: 10.0.19042.1288
View patch
microsoftpatch availablevia msrc
Product: Windows 10 Version 20H2 for ARM64-based SystemsFixed in: 10.0.19042.1288
View patch
microsoftpatch availablevia msrc
Product: Windows Server, version 20H2 (Server Core Installation)Fixed in: 10.0.19042.1288
View patch
microsoftpatch availablevia msrc
Product: Windows 11 version 21H2 for x64-based SystemsFixed in: 10.0.22000.258
View patch
microsoftpatch availablevia msrc
Product: Windows 11 version 21H2 for ARM64-based SystemsFixed in: 10.0.22000.258
View patch
microsoftpatch availablevia msrc
Product: Windows 10 for 32-bit SystemsFixed in: 10.0.10240.19086
View patch
microsoftpatch availablevia msrc
Product: Windows 10 for x64-based SystemsFixed in: 10.0.10240.19086
View patch
microsoftpatch availablevia msrc
Product: Windows 10 Version 1607 for 32-bit SystemsFixed in: 10.0.14393.4704
View patch
microsoftpatch availablevia msrc
Product: Windows 10 Version 1607 for x64-based SystemsFixed in: 10.0.14393.4704
View patch
microsoftpatch availablevia msrc
Product: Windows Server 2016Fixed in: 10.0.14393.4704
View patch
microsoftpatch availablevia msrc
Product: Windows Server 2016 (Server Core installation)Fixed in: 10.0.14393.4704
View patch
microsoftpatch availablevia msrc
Product: Windows 7 for 32-bit Systems Service Pack 1Fixed in: 6.1.7601.25740
View patch
microsoftpatch availablevia msrc
Product: Windows 7 for x64-based Systems Service Pack 1Fixed in: 6.1.7601.25740
View patch
microsoftpatch availablevia msrc
Product: Windows Server 2008 R2 for x64-based Systems Service Pack 1Fixed in: 6.1.7601.25740
View patch
microsoftpatch availablevia msrc
Product: Windows Server 2008 R2 for x64-based Systems Service Pack 1 (Server Core installation)Fixed in: 6.1.7601.25740
View patch
microsoftpatch availablevia msrc
Product: Windows 8.1 for 32-bit systemsFixed in: 6.3.9600.20144
View patch
microsoftpatch availablevia msrc
Product: Windows 8.1 for x64-based systemsFixed in: 6.3.9600.20144
View patch
microsoftpatch availablevia msrc
Product: Windows RT 8.1Fixed in: 6.3.9600.20144
View patch
microsoftpatch availablevia msrc
Product: Windows Server 2012 R2Fixed in: 6.3.9600.20144
View patch
microsoftpatch availablevia msrc
Product: Windows Server 2012 R2 (Server Core installation)Fixed in: 6.3.9600.20144
View patch
microsoftpatch availablevia msrc
Product: Windows Server 2008 for 32-bit Systems Service Pack 2Fixed in: 6.0.6003.21251
View patch
microsoftpatch availablevia msrc
Product: Windows Server 2008 for 32-bit Systems Service Pack 2 (Server Core installation)Fixed in: 6.0.6003.21251
View patch
microsoftpatch availablevia msrc
Product: Windows Server 2008 for x64-based Systems Service Pack 2Fixed in: 6.0.6003.21251
View patch
microsoftpatch availablevia msrc
Product: Windows Server 2008 for x64-based Systems Service Pack 2 (Server Core installation)Fixed in: 6.0.6003.21251
View patch
microsoftpatch availablevia msrc
Product: Windows Server 2012Fixed in: 6.2.9200.23490
View patch
microsoftpatch availablevia msrc
Product: Windows Server 2012 (Server Core installation)Fixed in: 6.2.9200.23490
View patch

Vendor Advisories (1)

microsoft2021-Oct/CVE-2021-40466Important

Windows Common Log File System Driver Elevation of Privilege Vulnerability

Oct 12, 2021

References

portal.msrc.microsoft.com / en-US/security-guidance/advisory/CVE-2021-40466
PatchVendor Advisory