dbcve.org
Windows 10 1607Operating system · Microsoft

CVE-2026-20826

HIGH · 7.0 CVSS v3.1 Published 2026-01-13
Fix available
A fix is available. Upgrade to 10.0.14393.8783 / 10.0.17763.8276 or later.
See remediation →
72/100
Remediation priority · Elevated
Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
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.

In the news

Third-party coverage
Trending covered by 1 outlet this week · latest 7mo ago

Surfaced from public web coverage — external links open in a new tab.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · moderate confidence

A race condition vulnerability exists in the Tablet Windows User Interface (TWINUI) subsystem where concurrent execution of shared resources occurs without proper synchronization. An authorized attacker with local access can exploit this timing vulnerability to elevate privileges to higher permission levels.

MitigationApply vendor-supplied Windows security updates addressing the TWINUI race condition. Ensure least-privilege access controls and monitor for suspicious processes targeting UI subsystem components.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Windows 10 1607Operating system
Affected:< 10.0.14393.8783
Windows 10 1809Operating system
Affected:< 10.0.17763.8276
Windows 10 21h2Operating system
Affected:< 10.0.19044.6809
Windows 10 22h2Operating system
Affected:< 10.0.19045.6809
Windows 11 23h2Operating system
Affected:< 10.0.22631.6491
Windows 11 24h2Operating system
Affected:< 10.0.26100.7623
Windows 11 25h2Operating system
Affected:< 10.0.26200.7623
Windows Server 2016Operating system
Affected:< 10.0.14393.8783

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Local
Complexity
High
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

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

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify Windows version and build number
    Run 'winver' from command prompt or execute 'systeminfo | findstr /B /C:"OS Name" /C:"OS Version"' to retrieve the exact build version
    Affected if The build number falls below any of these thresholds: 14393.8783 (Win10 1607/Server2016), 17763.8276 (Win10 1809), 19044.6809 (Win10 21h2/22h2), 22631.6491 (Win11 23h2), 26100.7623 (Win11 24h2), 26200.7623 (Win11 25h2)
  2. Confirm TWINUI subsystem component presence
    Check for the presence of TWINUI-related DLLs in the system: locate 'twinui.appcore.dll' in C:\Windows\System32 or C:\Windows\WinSxS directories
    Affected if The TWINUI DLL exists on the system (prerequisite for the vulnerability to be present)
  3. Verify current patch installation status
    Run 'wmic qfe list' or 'Get-HotFix' PowerShell command to enumerate installed security updates
    Affected if No security update matching the CVE-2026-20826 patch date is installed, and the Windows version falls within the affected build ranges

A system is affected if it runs any Windows 10/11 or Server 2016 version with a build number lower than the patched thresholds AND has the TWINUI subsystem component present.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 10.0.14393.8783 / 10.0.17763.8276 / 10.0.19044.6809 or later
Fixed in 10.0.14393.878310.0.17763.827610.0.19044.6809
Interim mitigation

Apply vendor-supplied Windows security updates addressing the TWINUI race condition. Ensure least-privilege access controls and monitor for suspicious processes targeting UI subsystem components.

Recommended fix High confidence

Windows 10 1607: 10.0.14393.8783 | Windows 10 1809: 10.0.17763.8276 | Windows 10 21h2: 10.0.19044.6809 | Windows 10 22h2: 10.0.19045.6809 | Windows 11 23h2: 10.0.22631.6491 | Windows 11 24h2: 10.0.26100.7623 | Windows 11 25h2: 10.0.26200.7623 | Windows Server 2016: 10.0.14393.8783

  1. Open Windows Settings on the affected system
  2. Navigate to Windows Update (Settings > Windows Update)
  3. Click 'Check for updates' to download and install the latest security updates
  4. Ensure the system restarts if prompted to complete the installation
  5. Verify the installed build number matches or exceeds the fixed version for your Windows release
Caveat Standard Windows cumulative updates typically do not introduce breaking changes; verify compatibility with critical line-of-business applications before deployment in enterprise environments

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Windows 10 1607 Scoped from the published advisory
  • Consultation8.0 h
  • Implementation16.0 h
  • Testing8.0 h
  • Review / QA4.0 h
36.0 hours of engineering $6,400
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Scan for this in your stack

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-20826 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data