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Windows 11 23h2Operating system · Microsoft

CVE-2026-27907

HIGH · 7.8 CVSS v3.1 Published 2026-04-14
Fix available
A fix is available. Upgrade to 10.0.22631.6936 / 10.0.25398.2274 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
Integer underflow (wrap or wraparound) in Windows Storage Spaces Controller allows an authorized attacker to elevate privileges 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

An integer underflow vulnerability in the Windows Storage Spaces Controller allows a local authenticated attacker to elevate privileges to higher permission levels. The flaw occurs when the controller improperly handles arithmetic operations, causing wraparound that can be exploited to execute code with elevated system rights.

MitigationApply Microsoft security updates for Windows when released for this vulnerability. Prioritize patching systems with Storage Spaces configured. As an interim measure, limit local user privileges and monitor for unauthorized privilege escalation attempts.

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 11 23h2Operating system
Affected:< 10.0.22631.6936
Windows 11 24h2Operating system
Affected:< 10.0.26100.8246
Windows 11 25h2Operating system
Affected:< 10.0.26200.8246
Windows 11 26h1Operating system
Affected:< 10.0.28000.1836
Windows Server 2022 23h2Operating system
Affected:< 10.0.25398.2274
Windows Server 2025Operating system
Affected:< 10.0.26100.32690

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
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:L/AC:L/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
    Run 'winver' from command prompt or check the registry key 'HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion' for the Build Number and DisplayVersion. Compare against affected version ranges: 23h2 (build <22631.6936), 24h2 (build <26100.8246), 25h2 (build <26200.8246), 26h1 (build <28000.1836). For Server: 2022 23h2 (build <25398.2274), Server 2025 (build <26100.32690).
    Affected if The installed Windows version falls within any of the listed affected version ranges.
  2. Verify Storage Spaces feature status
    Open PowerShell and run 'Get-PhysicalDisk' to list physical disks managed by Storage Spaces, or run 'Get-StorageSpaces' to check for any configured storage spaces. Also check if the 'Storage Spaces' service is present and not disabled.
    Affected if Storage Spaces is configured and the Storage Spaces Controller service is available on the system.
  3. Confirm local authenticated access
    Verify that a local user account exists on the system (checked via 'net user' or Local Users and Groups). The vulnerability requires a local authenticated attacker to exploit the integer underflow.
    Affected if There are local user accounts on the system that could potentially exploit this flaw.

A system is affected if it runs any of the listed Windows versions AND has Storage Spaces configured or the Storage Spaces Controller service available, allowing a local authenticated user to potentially trigger the integer underflow for privilege escalation.

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 10.0.22631.6936 / 10.0.25398.2274 / 10.0.26100.8246 or later
Fixed in 10.0.22631.693610.0.25398.227410.0.26100.8246
Interim mitigation

Apply Microsoft security updates for Windows when released for this vulnerability. Prioritize patching systems with Storage Spaces configured. As an interim measure, limit local user privileges and monitor for unauthorized privilege escalation attempts.

Recommended fix High confidence

Windows 11 23h2: 10.0.22631.6936 or later | Windows 11 24h2: 10.0.26100.8246 or later | Windows 11 25h2: 10.0.26200.8246 or later | Windows 11 26h1: 10.0.28000.1836 or later | Windows Server 2022 23h2: 10.0.25398.2274 or later | Windows Server 2025: 10.0.26100.32690 or later

  1. Open Settings > Windows Update and check for available updates
  2. Install all pending Windows updates, particularly security updates for the Storage Spaces Controller component
  3. Restart the system if prompted to complete the update installation
  4. Verify the installed version by running 'winver' or 'systeminfo' and confirm the build number meets 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 11 23h2 Scoped from the published advisory
  • Consultation4.0 h
  • Implementation6.0 h
  • Testing4.0 h
  • Review / QA2.0 h
16.0 hours of engineering $2,840
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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-2026-27907 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