CVE-2026-20861
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 · uneditedConcurrent execution using shared resource with improper synchronization ('race condition') in Windows Management Services allows an authorized attacker to elevate privileges locally.
In the news
Third-party coverage- Microsoft January 2026 Patch Tuesday fixes 3 zero-days, 114 flaws
- Microsoft CVE Summary - Bleeping Computer
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 confidenceA race condition vulnerability exists in Windows Management Services where concurrent execution with improper synchronization allows an authorized local attacker to manipulate shared resources and elevate privileges to higher permission levels.
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< 10.0.17763.8276< 10.0.19044.6809< 10.0.19045.6809< 10.0.22631.6491< 10.0.26100.7623< 10.0.26200.7623< 10.0.17763.8276< 10.0.20348.4648CVSS 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
- Changed
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/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 checksWork through these to decide whether this CVE applies to you.
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Check Windows version against affected rangesRun 'winver' or 'systeminfo | findstr /B /C:"OS Name" /C:"OS Version"' to obtain the installed Windows version and build numberAffected if The installed version is lower than any of these thresholds: 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 2019 < 10.0.17
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Verify Windows Management Services statusOpen Services console (services.msc) and locate 'Windows Management Service' or run 'Get-Service | Where-Object {$_.Name -like "*Management*"}' in PowerShell to check if the service exists and its current stateAffected if Windows Management Service is present and running on an affected Windows version
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Check for unauthorized local user accountsRun 'net user' in Command Prompt to list all local users, then review user memberships using 'net localgroup' to identify users with elevated privilegesAffected if Multiple local user accounts exist with administrative privileges on an affected system, increasing the attack surface for this local privilege escalation flaw
A system is likely affected if it runs any of the listed Windows versions below the specified build thresholds and has Windows Management Services enabled with multiple local users present.
Generated from the published advisory. Verify against your own configuration.
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 · scoped10.0.17763.827610.0.19044.680910.0.19045.6809
Apply available Microsoft security updates for Windows Management Services; until a patch is released, minimize the number of authorized local users and monitor for suspicious process activity targeting WMS components.
Windows 10 1809: build 10.0.17763.8276 | Windows 10 21h2: build 10.0.19044.6809 | Windows 10 22h2: build 10.0.19045.6809 | Windows 11 23h2: build 10.0.22631.6491 | Windows 11 24h2: build 10.0.26100.7623 | Windows 11 25h2: build 10.0.26200.7623 | Windows Server 2019: build 10.0.17763.8276 | Windows S
- Identify the current Windows version and build number by running 'winver' or 'systeminfo' in Command Prompt
- Determine which version category your system falls into (Windows 10 1809, 21h2, 22h2, Windows 11 23h2, 24h2, 25h2, Windows Server 2019, or Windows Server 2022)
- Open Settings > Windows Update and check for updates, or manually download the appropriate security update from the Microsoft Update Catalog
- Install the corresponding security update: For Windows 10 1809/Windows Server 2019, install build 10.0.17763.8276 or later; For Windows 10 21h2, install build 10.0.19044.6809 or later; For Windows 10 22h2, install build 10.0.19045.6809 or later; For Windows 11 23h2, install build 10.0.22631.6491 or later; For Windows 11 24h2, install build 10.0.26100.7623 or later; For Windows 11 25h2, install bui
- Restart the system when prompted to complete the installation
- Verify the update was successful by checking the build number in winver
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation4.0 h
- Implementation4.0 h
- Testing4.0 h
- Review / QA2.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-20861 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2026-20861 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- 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
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