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CVE-2021-43239

25
FAUCET Score

CVE-2021-43239 is an Elevation of Privilege vulnerability affecting the Windows Recovery Environment Agent across various Windows 10, 11, and Server versions. With a CVSS score of 7.8 (High), it allows a local attacker with low privileges to achieve full confidentiality, integrity, and availability impact without user interaction. While no public exploit code or active exploitation is reported, its presence on Microsoft's December 2021 Patch Tuesday highlights its significance. Community discussion and media coverage are minimal, suggesting limited public awareness despite its high severity.

Impacted Technologies

VendorProductVersion(s)CPE
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:*
21h1CPE matchmatch criteria
cpe:2.3:o:microsoft:windows_10:21h1:*:*:*:*:*:arm64:*
21h1CPE matchmatch criteria
cpe:2.3:o:microsoft:windows_10:21h1:*:*:*:*:*:x64:*

CVSS Data

CVSS version used by this source: 3.1

7.1HIGH

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

Attack Vector
LOCAL
Attack Complexity
LOW
Privileges Required
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
HIGH
Availability Impact
HIGH
Exploitability Score
1.8
Impact Score
5.2
CvssVersion
3.1

Exploit Intelligence

EPSS Score
0.54%
Probability of exploitation in next 30 days
EPSS Percentile
42.5%
Percentile rank of EPSS score among Peer Group
As of 2026-07-28
Model: v2026.06.15
This CVE's current EPSS score of 0.0054 is in the 82nd 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 (18)

microsoftpatch availablevia nvd_reference
View patch
microsoftpatch availablevia msrc
Product: Windows 10 Version 21H1 for x64-based SystemsFixed in: 10.0.19043.1415
View patch
microsoftpatch availablevia msrc
Product: Windows 10 Version 21H1 for ARM64-based SystemsFixed in: 10.0.19043.1415
View patch
microsoftpatch availablevia msrc
Product: Windows 10 Version 21H1 for 32-bit SystemsFixed in: 10.0.19043.1415
View patch
microsoftpatch availablevia msrc
Product: Windows Server 2022Fixed in: 10.0.20348.405
View patch
microsoftpatch availablevia msrc
Product: Windows Server 2022 (Server Core installation)Fixed in: 10.0.20348.405
View patch
microsoftpatch availablevia msrc
Product: Windows 10 Version 2004 for 32-bit SystemsFixed in: 10.0.19041.1415
View patch
microsoftpatch availablevia msrc
Product: Windows 10 Version 2004 for ARM64-based SystemsFixed in: 10.0.19041.1415
View patch
microsoftpatch availablevia msrc
Product: Windows 10 Version 2004 for x64-based SystemsFixed in: 10.0.19041.1415
View patch
microsoftpatch availablevia msrc
Product: Windows Server, version 2004 (Server Core installation)Fixed in: 10.0.19041.1415
View patch
microsoftpatch availablevia msrc
Product: Windows 10 Version 20H2 for 32-bit SystemsFixed in: 10.0.19042.1415
View patch
microsoftpatch availablevia msrc
Product: Windows 10 Version 20H2 for ARM64-based SystemsFixed in: 10.0.19042.1415
View patch
microsoftpatch availablevia msrc
Product: Windows Server, version 20H2 (Server Core Installation)Fixed in: 10.0.19042.1415
View patch
microsoftpatch availablevia msrc
Product: Windows 11 version 21H2 for x64-based SystemsFixed in: 10.0.22000.376
View patch
microsoftpatch availablevia msrc
Product: Windows 11 version 21H2 for ARM64-based SystemsFixed in: 10.0.22000.376
View patch
microsoftpatch availablevia msrc
Product: Windows 10 Version 21H2 for 32-bit SystemsFixed in: 10.0.19044.1415
View patch
microsoftpatch availablevia msrc
Product: Windows 10 Version 21H2 for ARM64-based SystemsFixed in: 10.0.19044.1415
View patch
microsoftpatch availablevia msrc
Product: Windows 10 Version 21H2 for x64-based SystemsFixed in: 10.0.19044.1415
View patch

Vendor Advisories (1)

microsoft2021-Dec/CVE-2021-43239Important

Windows Recovery Environment Agent Elevation of Privilege Vulnerability

Dec 14, 2021

References

portal.msrc.microsoft.com / en-US/security-guidance/advisory/CVE-2021-43239
PatchVendor Advisory