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ReviewHigh

CVE-2026-66802

Microsoft Windows 10 Version 1809, Windows 11 version 26H1, Windows Server 2019

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.

CVSS
8.1
EPSS
-
- percentile
CISA KEV
Not listed
Published
2026.08.12
PRIORITY ASSESSMENT

Review

The CVSS severity warrants an early asset and exposure review.

Known exploitationNot established by KEV
Exploit probability-
Technical severityCVSS 8.1

Vulnerability overview

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.

Affected product and versions

Product
Microsoft Windows 10 Version 1809, Windows 11 version 26H1, Windows Server 2019
Affected versions
>= 10.0.17763.0 < 10.0.17763.9121, >= 10.0.28000.0 < 10.0.28000.2704, >= 10.0.20348.0 < 10.0.20348.5499, >= 10.0.26100.0 < 10.0.26100.33296, < 10.0.20348.5440, < 10.0.26100.33222
Fixed versions
Verify the fixed release separately for each affected product line

Recommended response sequence

Confirm exposure before applying a vendor-supported change.

Full remediation guide
  1. 1
    Identify

    Confirm that Microsoft Windows 10 Version 1809, Windows 11 version 26H1, Windows Server 2019 and an affected version are present.

  2. 2
    Prioritize

    Combine exploitation signals with asset exposure and business criticality.

  3. 3
    Remediate

    Follow the vendor advisory or supported update path and preserve rollback options.

  4. 4
    Verify

    Recheck the version, service health, access paths, and relevant logs.

Technical data

CVSS vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
CWE
CWE-362, CWE-416
CVE-2026-66802 — Microsoft Windows 10 Version 1809, Windows 11 version 26H1, Windows Server 2019 | SECUFOCUS NOW