Microsoft Security Response CenterCVE-2026-66802

Windows Device Health Attestation (DHA) Remote Code Execution Vulnerability

Concurrent execution using shared resource with improper synchronization ('race condition') in Windows Device Health Attestation (DHA) allows an unauthorized attacker to execute code over a network.

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8.1CVSS out of 10Critical severity

Scope

What the vendor says is affected

Windows 10 Version 1809 for 32-bit Systems
Windows 10 Version 1809 for x64-based Systems
Windows Server 2019
Windows Server 2019 (Server Core installation)
Windows Server 2022
Windows Server 2022 (Server Core installation)
Windows Server 2025 (Server Core installation)
Windows Server 2025
Windows 11 version 26H1 for x64-based Systems
Windows 11 Version 26H1 for ARM64-based Systems

Versions the vendor lists as fixed

10.0.17763.9121
10.0.20348.5499
10.0.20348.5440
10.0.26100.33296
10.0.26100.33222
10.0.28000.2704

Next step

What the vendor recommends

Install KB5120238. Install KB5120242. Install KB5120229. Install KB5120233. Install KB5120228. Install KB5121000.

Review the complete instructions on the vendor's site

Update history

What changed in later vendor updates

SecurityAlert records field-level changes from the point we begin following a bulletin. Earlier vendor changes may not have a field-by-field record.

Aug 20, 2026 at 7:00 PM UTC
- The vendor changed its remediation guidance.

Timeline

When this advisory changed

Aug 11, 2026 at 7:00 AM UTC
Published by Microsoft Security Response Center
The publication date reported by the vendor.
Aug 20, 2026 at 7:00 AM UTC
Updated by Microsoft Security Response Center
The vendor changed the advisory after it was first published.
Aug 20, 2026 at 6:50 PM UTC
Added to SecurityAlert
We collected the advisory from the official source.
Sep 2, 2026 at 5:15 PM UTC
Confirmed at the source
Our collector saw this advisory during a later source check.

Vulnerabilities

CVEs named in this advisory

CVE-2026-66802View CVSS, KEV, EPSS, and threat context

Source

Start with the vendor's bulletin

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Vendor: Microsoft Security Response Center
Advisory ID: CVE-2026-66802
Last source check: Sep 13, 2026 at 2:40 AM UTC

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What the vendor says is affected

Versions the vendor lists as fixed

What the vendor recommends

What changed in later vendor updates

When this advisory changed

CVEs named in this advisory

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