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Windows 10 1607Operating system · Microsoft

CVE-2026-21244

HIGH · 7.3 CVSS v3.1 Published 2026-02-10
Fix available
A fix is available. Upgrade to 10.0.14393.8868 / 10.0.17763.8389 or later.
See remediation →
73/100
Remediation priority · Elevated

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
Heap-based buffer overflow in Windows Hyper-V allows an authorized attacker to execute code locally.

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

Heap-based buffer overflow in Windows Hyper-V allows an authorized attacker to execute arbitrary code locally through heap memory corruption.

MitigationApply Microsoft security patches for this vulnerability to Hyper-V hosts during a planned maintenance window, as this is a hypervisor-level fix that may require host reboots.

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:< 10.0.14393.8868
Windows 10 1809Operating system
Affected:< 10.0.17763.8389
Windows 10 21h2Operating system
Affected:< 10.0.19044.6937
Windows 10 22h2Operating system
Affected:< 10.0.19045.6937
Windows 11 23h2Operating system
Affected:< 10.0.22631.6649
Windows 11 24h2Operating system
Affected:< 10.0.26100.7781
Windows 11 25h2Operating system
Affected:< 10.0.26200.7781
Windows Server 2016Operating system
Affected:< 10.0.14393.8868

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
Low
Privileges
Low
User interaction
Required
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:L/AC:L/PR:L/UI:R/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. Verify Hyper-V hypervisor is installed
    Run 'systeminfo' in Command Prompt and look for 'Hyper-V' under 'Hyper-V Requirements' or run 'Get-WindowsOptionalFeature -Online -FeatureName Microsoft-Hyper-V' in PowerShell
    Affected if Hyper-V is listed as installed or enabled - the vulnerability only applies when the Hyper-V role is present
  2. Check Windows version number
    Run 'winver' or 'systeminfo' and note the OS Build number (e.g., 19045.6937), or run 'reg query "HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion" /v CurrentBuild' in Command Prompt
    Affected if The installed version is lower than any of these thresholds: Windows 10 1607/Server 2016 < 10.0.14393.8868, Windows 10 1809 < 10.0.17763.8389, Windows 10 21h2 < 10.0.19044.6937, Windows 10 22h2 < 10.0.19045.6937, Windows 11 23h2 < 10.0.22631.6649, Windows 11 24h2 < 10.0.26100.7781, Windows 11 25h2 <
  3. Confirm Hyper-V services are running
    Run 'Get-Service vmcompute, vmms, vmwp' in PowerShell or 'sc query vmcompute, vmms, vmwp' in Command Prompt
    Affected if Any of these services are in a Running state - the vulnerability is exploitable when the Hyper-V stack is active

You are affected if Hyper-V is installed and your Windows version/build number falls below the fixed thresholds listed for your Windows release.

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 10.0.14393.8868 / 10.0.17763.8389 / 10.0.19044.6937 or later
Fixed in 10.0.14393.886810.0.17763.838910.0.19044.6937
Interim mitigation

Apply Microsoft security patches for this vulnerability to Hyper-V hosts during a planned maintenance window, as this is a hypervisor-level fix that may require host reboots.

Recommended fix High confidence

Install the corresponding Windows security update (KB article from Microsoft) that addresses CVE-2026-21244, which will upgrade the build to: 10.0.14393.8868 (Windows 10 1607/Server 2016), 10.0.17763.8389 (Windows 10 1809), 10.0.19044.6937 (Windows 10 21h2), 10.0.19045.6937 (Windows 10 22h2), 10.0.2

  1. 1. Identify the current Windows version and build number by running `winver` or `systeminfo` in Command Prompt
  2. 2. Determine if the system is affected by comparing the current build to the vulnerable versions listed (< 10.0.14393.8868 for Windows 10 1607/Server 2016, < 10.0.17763.8389 for Windows 10 1809, < 10.0.19044.6937 for Windows 10 21h2, < 10.0.19045.6937 for Windows 10 22h2, < 10.0.22631.6649 for Windows 11 23h2, < 10.0.26100.7781 for Windows 11 24h2, < 10.0.26200.7781 for Windows 11 25h2)
  3. 3. Open Windows Settings and navigate to Windows Update, or run `ms-settings:windowsupdate`
  4. 4. Check for updates and install all available security updates
  5. 5. If updates are not available through Windows Update, manually download the specific security update from the Microsoft Update Catalog (search for the KB article associated with this CVE)
  6. 6. Restart the system after installing updates
  7. 7. Verify the fix by checking the build number has been updated to or above the fixed version for your Windows release
Caveat Standard Windows security update - minimal risk of breaking changes; as a precaution, backup critical VMs and data before applying updates to Hyper-V hosts

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

Fix this in Windows 10 1607 Scoped from the published advisory
  • Consultation4.0 h
  • Implementation12.0 h
  • Testing8.0 h
  • Review / QA4.0 h
28.0 hours of engineering $4,880
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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-2026-21244 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