dbcve.org
Windows 10 1809Operating system · Microsoft

CVE-2026-20858

HIGH · 7.8 CVSS v3.1 Published 2026-01-13
Fix available
A fix is available. Upgrade to 10.0.17763.8276 / 10.0.19044.6809 or later.
See remediation →
80/100
Remediation priority · High
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
Use after free in Windows Management Services 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 use-after-free vulnerability in Windows Management Services allows a local authenticated attacker to gain elevated privileges. The flaw occurs when the service continues using memory after it has been freed, potentially enabling arbitrary code execution with elevated context.

MitigationApply Microsoft security updates for Windows Management Services once released. Prioritize patching systems with local user access as the CVSS vector indicates local attack vector.

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 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 2019Operating system
Affected:< 10.0.17763.8276
Windows Server 2022Operating system
Affected:< 10.0.20348.4648

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
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 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 check 'systeminfo | findstr /B /C:"OS Name" /C:"OS Version"' to obtain the full build number (e.g., 10.0.17763.8276)
    Affected if The displayed build number is lower than the threshold for your Windows edition (see affected versions list)
  2. Confirm Windows Management Services component exists
    Check for the presence of Windows Management Services by running 'Get-WmiObject Win32_Service | Where-Object {$_.Name -like "*WinMgmt*"}' in PowerShell, or inspect services.msc for Windows Management Instrumentation service
    Affected if The Windows Management Instrumentation (WMI) service is installed on the system
  3. Verify service status
    Run 'Get-Service WinMgmt' in PowerShell or check the service status in services.msc to determine if the Windows Management Instrumentation service is running
    Affected if The service is in a running state, making the vulnerable code path potentially reachable
  4. Cross-reference build against CVE thresholds
    Compare your identified build number to the affected ranges: Windows 10 1809/Server 2019 < 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 2022 < 10.0.20348.4648
    Affected if Your build number falls below the specified threshold for your Windows version

You are affected if your Windows build number is below the threshold for your specific Windows edition AND the Windows Management Instrumentation service is present on the system.

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 10.0.17763.8276 / 10.0.19044.6809 / 10.0.19045.6809 or later
Fixed in 10.0.17763.827610.0.19044.680910.0.19045.6809
Interim mitigation

Apply Microsoft security updates for Windows Management Services once released. Prioritize patching systems with local user access as the CVSS vector indicates local attack vector.

Recommended fix High confidence

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: 10.0.17763.8276 | Windows Server 2022: 10.0.20348.4648

  1. Open Windows Update by pressing the Windows key + I, then selecting Update & Security > Windows Update
  2. Click 'Check for updates' to scan for available updates
  3. Install all cumulative security updates that include the fix for CVE-2026-20858 (refer to Microsoft Security Response Center for the specific KB article)
  4. Restart the system after installing updates
  5. Verify the installed version matches or exceeds the fixed version for your Windows edition

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

Fix this in Windows 10 1809 Scoped from the published advisory
  • Consultation3.0 h
  • Implementation4.0 h
  • Testing3.0 h
  • Review / QA2.0 h
12.0 hours of engineering $2,130
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $3,408.

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-2026-20858 in production — separate from our analysis above.

No notes yet

Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.

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