CVE-2021-43893

30

FAUCET Score

CVE-2021-43893 is an Elevation of Privilege vulnerability in the Windows Encrypting File System (EFS), impacting numerous Microsoft Windows client and server operating systems. With a CVSS score of 7.5 (HIGH), it presents a significant risk, allowing an attacker with low privileges to achieve high impact on confidentiality, integrity, and availability through a high complexity network attack. While not listed on the KEV catalog, this vulnerability has garnered notable community discussion and media coverage, though no public exploit code is currently available.

Impacted Technologies

Vendor	Product	Version(s)	CPE
		Range not provided by sourceCPE matchmatch criteria	cpe:2.3:o:microsoft:windows_10:-::::::x64:
		Range not provided by sourceCPE matchmatch criteria	cpe:2.3:o:microsoft:windows_10:-::::::x86:
		20h2CPE matchmatch criteria	cpe:2.3:o:microsoft:windows_10:20h2::::::arm64:
		20h2CPE matchmatch criteria	cpe:2.3:o:microsoft:windows_10:20h2::::::x64:
		20h2CPE matchmatch criteria	cpe:2.3:o:microsoft:windows_10:20h2::::::x86:

CVSS Data

CVSS version used by this source: 3.1

7.5HIGH

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

Attack Vector

NETWORK

Attack Complexity

HIGH

Privileges Required

LOW

User Interaction

NONE

Scope

UNCHANGED

Confidentiality Impact

HIGH

Integrity Impact

HIGH

Availability Impact

HIGH

Exploitability Score

1.6

Impact Score

5.9

CvssVersion

3.1

Exploit Intelligence

EPSS Score

6.62%

Probability of exploitation in next 30 days

EPSS Percentile

93.1%

Percentile rank of EPSS score among Peer Group

As of 2026-07-28

Model: v2026.06.15

This CVE's current EPSS score of 0.0662 is in the 93rd percentile among its peer group of 1,162 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 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (49)

microsoftpatch availablevia nvd_reference

microsoftpatch availablevia msrc

Product: Windows 10 Version 1809 for 32-bit SystemsFixed in: 10.0.17763.2366

microsoftpatch availablevia msrc

Product: Windows 10 Version 1809 for x64-based SystemsFixed in: 10.0.17763.2366

microsoftpatch availablevia msrc

Product: Windows 10 Version 1809 for ARM64-based SystemsFixed in: 10.0.17763.2366

microsoftpatch availablevia msrc

Product: Windows Server 2019Fixed in: 10.0.17763.2366

microsoftpatch availablevia msrc

Product: Windows Server 2019 (Server Core installation)Fixed in: 10.0.17763.2366

microsoftpatch availablevia msrc

Product: Windows 10 Version 1909 for 32-bit SystemsFixed in: 10.0.18363.1977

microsoftpatch availablevia msrc

Product: Windows 10 Version 1909 for x64-based SystemsFixed in: 10.0.18363.1977

microsoftpatch availablevia msrc

Product: Windows 10 Version 1909 for ARM64-based SystemsFixed in: 10.0.18363.1977

microsoftpatch availablevia msrc

Product: Windows 10 Version 21H1 for x64-based SystemsFixed in: 10.0.19043.1415

microsoftpatch availablevia msrc

Product: Windows 10 Version 21H1 for ARM64-based SystemsFixed in: 10.0.19043.1415

microsoftpatch availablevia msrc

Product: Windows 10 Version 21H1 for 32-bit SystemsFixed in: 10.0.19043.1415

microsoftpatch availablevia msrc

Product: Windows Server 2022Fixed in: 10.0.20348.405

microsoftpatch availablevia msrc

Product: Windows Server 2022 (Server Core installation)Fixed in: 10.0.20348.405

microsoftpatch availablevia msrc

Product: Windows 10 Version 2004 for 32-bit SystemsFixed in: 10.0.19041.1415

microsoftpatch availablevia msrc

Product: Windows 10 Version 2004 for ARM64-based SystemsFixed in: 10.0.19041.1415

microsoftpatch availablevia msrc

Product: Windows 10 Version 2004 for x64-based SystemsFixed in: 10.0.19041.1415

microsoftpatch availablevia msrc

Product: Windows Server, version 2004 (Server Core installation)Fixed in: 10.0.19041.1415

microsoftpatch availablevia msrc

Product: Windows 10 Version 20H2 for 32-bit SystemsFixed in: 10.0.19042.1415

microsoftpatch availablevia msrc

Product: Windows 10 Version 20H2 for ARM64-based SystemsFixed in: 10.0.19042.1415

microsoftpatch availablevia msrc

Product: Windows Server, version 20H2 (Server Core Installation)Fixed in: 10.0.19042.1415

microsoftpatch availablevia msrc

Product: Windows 11 version 21H2 for x64-based SystemsFixed in: 10.0.22000.376

microsoftpatch availablevia msrc

Product: Windows 11 version 21H2 for ARM64-based SystemsFixed in: 10.0.22000.376

microsoftpatch availablevia msrc

Product: Windows 10 Version 21H2 for 32-bit SystemsFixed in: 10.0.19044.1415

microsoftpatch availablevia msrc

Product: Windows 10 Version 21H2 for ARM64-based SystemsFixed in: 10.0.19044.1415

microsoftpatch availablevia msrc

Product: Windows 10 Version 21H2 for x64-based SystemsFixed in: 10.0.19044.1415

microsoftpatch availablevia msrc

Product: Windows 10 for 32-bit SystemsFixed in: 10.0.10240.19145

microsoftpatch availablevia msrc

Product: Windows 10 for x64-based SystemsFixed in: 10.0.10240.19145

microsoftpatch availablevia msrc

Product: Windows 10 Version 1607 for 32-bit SystemsFixed in: 10.0.14393.4825

microsoftpatch availablevia msrc

Product: Windows 10 Version 1607 for x64-based SystemsFixed in: 10.0.14393.4825

microsoftpatch availablevia msrc

Product: Windows Server 2016Fixed in: 10.0.14393.4825

microsoftpatch availablevia msrc

Product: Windows Server 2016 (Server Core installation)Fixed in: 10.0.14393.4825

microsoftpatch availablevia msrc

Product: Windows 7 for 32-bit Systems Service Pack 1Fixed in: 6.1.7601.25796

microsoftpatch availablevia msrc

Product: Windows 7 for x64-based Systems Service Pack 1Fixed in: 6.1.7601.25796

microsoftpatch availablevia msrc

Product: Windows Server 2008 R2 for x64-based Systems Service Pack 1Fixed in: 6.1.7601.25796

microsoftpatch availablevia msrc

Product: Windows Server 2008 R2 for x64-based Systems Service Pack 1 (Server Core installation)Fixed in: 6.1.7601.25796

microsoftpatch availablevia msrc

Product: Windows 8.1 for 32-bit systemsFixed in: 6.3.9600.20207

microsoftpatch availablevia msrc

Product: Windows 8.1 for x64-based systemsFixed in: 6.3.9600.20207

microsoftpatch availablevia msrc

Product: Windows RT 8.1Fixed in: 6.3.9600.20207

microsoftpatch availablevia msrc

Product: Windows Server 2012 R2Fixed in: 6.3.9600.20207

microsoftpatch availablevia msrc

Product: Windows Server 2012 R2 (Server Core installation)Fixed in: 6.3.9600.20207

microsoftpatch availablevia msrc

Product: Windows Server 2008 for 32-bit Systems Service Pack 2Fixed in: 6.0.6003.21309

microsoftpatch availablevia msrc

Product: Windows Server 2008 for 32-bit Systems Service Pack 2 (Server Core installation)Fixed in: 6.0.6003.21309

microsoftpatch availablevia msrc

Product: Windows Server 2008 for x64-based Systems Service Pack 2Fixed in: 6.0.6003.21309

microsoftpatch availablevia msrc

Product: Windows Server 2008 for x64-based Systems Service Pack 2 (Server Core installation)Fixed in: 6.0.6003.21309

microsoftpatch availablevia msrc

Product: Windows Server 2012Fixed in: 6.2.9200.23545

microsoftpatch availablevia msrc

Product: Windows Server 2012 (Server Core installation)Fixed in: 6.2.9200.23545

microsoftpatch availablevia msrc

Product: Windows Server 2012Fixed in: 6.2.9200.23540

microsoftpatch availablevia msrc

Product: Windows Server 2012 (Server Core installation)Fixed in: 6.2.9200.23540

Vendor Advisories (1)

microsoft2021-Dec/CVE-2021-43893Important

Windows Encrypting File System (EFS) Elevation of Privilege Vulnerability

References

packetstormsecurity.com / files/165560/Microsoft-Windows-EFSRPC-Arbitrary-File-Upload-Privilege-Escalation.html

Third Party AdvisoryVDB Entry

portal.msrc.microsoft.com / en-US/security-guidance/advisory/CVE-2021-43893

PatchVendor Advisory