Review reviewHigh

CVE-2026-20853

Microsoft Windows 10 Version 1607, Windows 10 Version 1809, Windows 10 Version 21H2

Concurrent execution using shared resource with improper synchronization ('race condition') in Windows WalletService allows an unauthorized attacker to elevate privileges locally.

CVSS: 7.4
EPSS: -
CISA KEV: Not listed
Published: 2026.01.14

PRIORITY ASSESSMENT

Review review

The CVSS severity warrants an early asset and exposure review.

Known exploitationNot established by KEV

Exploit probability-

Technical severityCVSS 7.4

Vulnerability overview

Concurrent execution using shared resource with improper synchronization ('race condition') in Windows WalletService allows an unauthorized attacker to elevate privileges locally.

Affected product and versions

Product: Microsoft Windows 10 Version 1607, Windows 10 Version 1809, Windows 10 Version 21H2
Affected versions: >= 10.0.14393.0 < 10.0.14393.8783, >= 10.0.17763.0 < 10.0.17763.8276, >= 10.0.19044.0 < 10.0.19044.6809, >= 10.0.19045.0 < 10.0.19045.6809, >= 10.0.22631.0 < 10.0.22631.6491, >= 10.0.26100.0 < 10.0.26100.7623, >= 10.0.26200.0 < 10.0.26200.7623, < 10.0.14393.8783, < 10.0.17763.8276, < 10.0.19044.6809, < 10.0.19045.6809, < 10.0.22631.6491, < 10.0.26100.7623, < 10.0.26200.7623
Fixed versions: 10.0.14393.8783, 10.0.17763.8276, 10.0.19044.6809, 10.0.19045.6809, 10.0.22631.6491, 10.0.26100.7623, 10.0.26200.7623

Recommended response sequence

Confirm exposure before applying a vendor-supported change.

Full remediation guide

1
Identify
Confirm that Microsoft Windows 10 Version 1607, Windows 10 Version 1809, Windows 10 Version 21H2 and an affected version are present.
2
Prioritize
Combine exploitation signals with asset exposure and business criticality.
3
Remediate
Follow the vendor advisory or supported update path and preserve rollback options.
4
Verify
Recheck the version, service health, access paths, and relevant logs.

Technical data

CVSS vector: CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
CWE: CWE-362