Description
Concurrent execution using shared resource with improper synchronization ('race condition') in Windows TCP/IP allows an authorized attacker to elevate privileges locally.
Published: 2026-04-14
Score: 7 High
EPSS: < 1% Very Low
KEV: No
Impact: Local Privilege Escalation
Action: Patch Immediately
AI Analysis

Impact

The vulnerability is a race condition in the Windows TDI Translation Driver (tdx.sys) that allows an authorized local attacker to elevate their privileges. Improper synchronization of a shared resource leads to an improper state that can be exploited to gain higher privileges. This weakness, identified as CWE-362 and CWE-416, can compromise confidentiality, integrity and availability by permitting an attacker with some local access to execute code with SYSTEM rights.

Affected Systems

Affected systems include Microsoft Windows 10 versions 1607, 1809, 21H2, and 22H2, and Windows 11 versions 23H2, 24H2, 25H2, 22H3, and 26H1, as well as Windows Server editions 2012, 2012 R2, 2016, 2019, 2022, 2025 and the 23H2 Server edition. Both Server Core installations and full desktop editions are affected across x86, x64 and ARM64 architectures where the tdx.sys driver is present.

Risk and Exploitability

The CVSS score of 7 indicates high severity, and although EPSS data is not available and the vulnerability is not listed in KEV, the presence of a Microsoft update suggests some exploitation risk in the wild. The attack requires local, authorized access to the target machine, making it a local privilege escalation vector. Operators should treat this as a priority update to prevent potential elevation of privileges by malicious scripts or applications running under user context.

Generated by OpenCVE AI on April 14, 2026 at 19:27 UTC.

Remediation

No vendor fix or workaround currently provided.

OpenCVE Recommended Actions

  • Apply the Microsoft security update available for CVE‑2026‑27921 to all Windows 10, 11, and Windows Server machines listed above.
  • Confirm the update was installed successfully by checking Windows Update history or the Microsoft update guide.
  • Once updated, review system logs to verify that tdx.sys is not misbehaving and that no local privilege escalation incidents occur.

Generated by OpenCVE AI on April 14, 2026 at 19:27 UTC.

Tracking

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Advisories

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History

Wed, 15 Apr 2026 21:15:00 +0000

Type Values Removed Values Added
First Time appeared Microsoft windows 10 21h2
Microsoft windows 10 22h2
Microsoft windows 11 22h3
Microsoft windows 11 23h2
Microsoft windows 11 24h2
Microsoft windows 11 25h2
Microsoft windows 11 26h1
Microsoft windows Server 2012 (server Core Installation)
Microsoft windows Server 2012 R2
Microsoft windows Server 2012 R2 (server Core Installation)
Microsoft windows Server 2016 (server Core Installation)
Microsoft windows Server 2019 (server Core Installation)
Microsoft windows Server 2022, 23h2 Edition (server Core Installation)
Microsoft windows Server 2025 (server Core Installation)
Vendors & Products Microsoft windows 10 21h2
Microsoft windows 10 22h2
Microsoft windows 11 22h3
Microsoft windows 11 23h2
Microsoft windows 11 24h2
Microsoft windows 11 25h2
Microsoft windows 11 26h1
Microsoft windows Server 2012 (server Core Installation)
Microsoft windows Server 2012 R2
Microsoft windows Server 2012 R2 (server Core Installation)
Microsoft windows Server 2016 (server Core Installation)
Microsoft windows Server 2019 (server Core Installation)
Microsoft windows Server 2022, 23h2 Edition (server Core Installation)
Microsoft windows Server 2025 (server Core Installation)

Wed, 15 Apr 2026 11:15:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'total'}, 'version': '2.0.3'}


Tue, 14 Apr 2026 17:30:00 +0000

Type Values Removed Values Added
Description Concurrent execution using shared resource with improper synchronization ('race condition') in Windows TCP/IP allows an authorized attacker to elevate privileges locally.
Title Windows TDI Translation Driver (tdx.sys) Elevation of Privilege Vulnerability
First Time appeared Microsoft
Microsoft windows 10 1607
Microsoft windows 10 1809
Microsoft windows 10 21h2
Microsoft windows 10 22h2
Microsoft windows 11 23h2
Microsoft windows 11 24h2
Microsoft windows 11 25h2
Microsoft windows 11 26h1
Microsoft windows Server 2012
Microsoft windows Server 2012 R2
Microsoft windows Server 2016
Microsoft windows Server 2019
Microsoft windows Server 2022
Microsoft windows Server 2025
Microsoft windows Server 23h2
Weaknesses CWE-362
CWE-416
CPEs cpe:2.3:o:microsoft:windows_10_1607:*:*:*:*:*:*:x86:*
cpe:2.3:o:microsoft:windows_10_1809:*:*:*:*:*:*:x86:*
cpe:2.3:o:microsoft:windows_10_21H2:*:*:*:*:*:*:x86:*
cpe:2.3:o:microsoft:windows_10_22H2:*:*:*:*:*:*:x64:*
cpe:2.3:o:microsoft:windows_11_23H2:*:*:*:*:*:*:arm64:*
cpe:2.3:o:microsoft:windows_11_23H2:*:*:*:*:*:*:x64:*
cpe:2.3:o:microsoft:windows_11_24H2:*:*:*:*:*:*:arm64:*
cpe:2.3:o:microsoft:windows_11_25H2:*:*:*:*:*:*:arm64:*
cpe:2.3:o:microsoft:windows_11_26H1:*:*:*:*:*:*:arm64:*
cpe:2.3:o:microsoft:windows_server_2012:*:*:*:*:*:*:x64:*
cpe:2.3:o:microsoft:windows_server_2012_R2:*:*:*:*:*:*:x64:*
cpe:2.3:o:microsoft:windows_server_2016:*:*:*:*:*:*:*:*
cpe:2.3:o:microsoft:windows_server_2019:*:*:*:*:*:*:*:*
cpe:2.3:o:microsoft:windows_server_2022:*:*:*:*:*:*:*:*
cpe:2.3:o:microsoft:windows_server_2025:*:*:*:*:*:*:*:*
cpe:2.3:o:microsoft:windows_server_23h2:*:*:*:*:*:*:*:*
Vendors & Products Microsoft
Microsoft windows 10 1607
Microsoft windows 10 1809
Microsoft windows 10 21h2
Microsoft windows 10 22h2
Microsoft windows 11 23h2
Microsoft windows 11 24h2
Microsoft windows 11 25h2
Microsoft windows 11 26h1
Microsoft windows Server 2012
Microsoft windows Server 2012 R2
Microsoft windows Server 2016
Microsoft windows Server 2019
Microsoft windows Server 2022
Microsoft windows Server 2025
Microsoft windows Server 23h2
References
Metrics cvssV3_1

{'score': 7, 'vector': 'CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C'}


Subscriptions

Microsoft Windows 10 1607 Windows 10 1809 Windows 10 21h2 Windows 10 21h2 Windows 10 22h2 Windows 10 22h2 Windows 11 22h3 Windows 11 23h2 Windows 11 23h2 Windows 11 24h2 Windows 11 24h2 Windows 11 25h2 Windows 11 25h2 Windows 11 26h1 Windows 11 26h1 Windows Server 2012 Windows Server 2012 (server Core Installation) Windows Server 2012 R2 Windows Server 2012 R2 Windows Server 2012 R2 (server Core Installation) Windows Server 2016 Windows Server 2016 (server Core Installation) Windows Server 2019 Windows Server 2019 (server Core Installation) Windows Server 2022 Windows Server 2022, 23h2 Edition (server Core Installation) Windows Server 2025 Windows Server 2025 (server Core Installation) Windows Server 23h2
cve-icon MITRE

Status: PUBLISHED

Assigner: microsoft

Published:

Updated: 2026-04-17T15:51:21.242Z

Reserved: 2026-02-24T21:35:49.687Z

Link: CVE-2026-27921

cve-icon Vulnrichment

Updated: 2026-04-15T09:09:26.912Z

cve-icon NVD

Status : Awaiting Analysis

Published: 2026-04-14T18:17:01.980

Modified: 2026-04-17T15:10:35.607

Link: CVE-2026-27921

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-04-15T21:00:09Z

Weaknesses