CVE-2026-20826: Tablet Windows User Interface (TWINUI) Subsystem Information Disclosure Vulnerability

Severity: high (CVSS 7.0 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.3% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-01-13 · updated 2026-07-30
Weakness: CWE-362

Description

Concurrent execution using shared resource with improper synchronization ('race condition') in Tablet Windows User Interface (TWINUI) Subsystem allows an authorized attacker to elevate privileges locally.

Affected products

Microsoft Windows 10 1607: before 10.0.14393.8783 — fixed in 10.0.14393.8783
Microsoft Windows 10: before 10.0.17763.8276 — fixed in 10.0.17763.8276
Microsoft Windows 10: before 10.0.19044.6809 — fixed in 10.0.19044.6809
Microsoft Windows 10: before 10.0.19045.6809 — fixed in 10.0.19045.6809
Microsoft Windows 11: before 10.0.22631.6491 — fixed in 10.0.22631.6491
Microsoft Windows 11: before 10.0.26100.7623 — fixed in 10.0.26100.7623
Microsoft Windows 11 25H2: before 10.0.26200.7623 — fixed in 10.0.26200.7623
Microsoft Windows Server 2016: before 10.0.14393.8783 — fixed in 10.0.14393.8783
Microsoft Windows Server 2019: before 10.0.17763.8276 — fixed in 10.0.17763.8276
Microsoft Windows Server 2022: before 10.0.20348.4648 — fixed in 10.0.20348.4648
Microsoft Windows Server 2022, 23H2 Edition (Server Core installation): before 10.0.25398.2092 — fixed in 10.0.25398.2092
Microsoft Windows Server 2025: before 10.0.26100.32230 — fixed in 10.0.26100.32230
Microsoft Windows 10 1607: from 10.0.14393.0 before 10.0.14393.8783 — fixed in 10.0.14393.8783
Microsoft Windows 10: from 10.0.17763.0 before 10.0.17763.8276 — fixed in 10.0.17763.8276
Microsoft Windows 10: from 10.0.19044.0 before 10.0.19044.6809 — fixed in 10.0.19044.6809
Microsoft Windows 10: from 10.0.19045.0 before 10.0.19045.6809 — fixed in 10.0.19045.6809
Microsoft Windows 11: from 10.0.22631.0 before 10.0.22631.6491 — fixed in 10.0.22631.6491
Microsoft Windows 11: from 10.0.26100.0 before 10.0.26100.7623 — fixed in 10.0.26100.7623
Microsoft Windows 11 25H2: from 10.0.26200.0 before 10.0.26200.7623 — fixed in 10.0.26200.7623
Microsoft Windows Server 2016: from 10.0.14393.0 before 10.0.14393.8783 — fixed in 10.0.14393.8783
Microsoft Windows Server 2019: from 10.0.17763.0 before 10.0.17763.8276 — fixed in 10.0.17763.8276
Microsoft Windows Server 2022: from 10.0.20348.0 before 10.0.20348.4648 — fixed in 10.0.20348.4648
Microsoft Windows Server 2022, 23H2 Edition (Server Core installation): from 10.0.25398.0 before 10.0.25398.2092 — fixed in 10.0.25398.2092
Microsoft Windows Server 2025: from 10.0.26100.0 before 10.0.26100.32230 — fixed in 10.0.26100.32230

How to fix

Upgrade to a fixed version: Microsoft Windows 10 1607 10.0.14393.8783; Microsoft Windows 10 10.0.17763.8276; Microsoft Windows 10 10.0.19044.6809; Microsoft Windows 10 10.0.19045.6809; Microsoft Windows 11 10.0.22631.6491; Microsoft Windows 11 10.0.26100.7623; Microsoft Windows 11 25H2 10.0.26200.7623; Microsoft Windows Server 2016 10.0.14393.8783; Microsoft Windows Server 2019 10.0.17763.8276; Microsoft Windows Server 2022 10.0.20348.4648; Microsoft Windows Server 2022, 23H2 Edition (Server Core installation) 10.0.25398.2092; Microsoft Windows Server 2025 10.0.26100.32230. Check the vendor advisory for mitigations.

References

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-20826

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