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Windows 10 21h2Operating system · Microsoft

CVE-2026-41088

HIGH · 7.8 CVSS v3.1 Published 2026-05-12
Fix available
A fix is available. Upgrade to 10.0.19044.7291 / 10.0.19045.7291 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
Access of resource using incompatible type ('type confusion') in Windows Ancillary Function Driver for WinSock 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

A type confusion vulnerability in the Windows Ancillary Function Driver for WinSock allows a locally authorized attacker to elevate privileges by exploiting improper type handling when accessing resources.

MitigationApply the Microsoft security update for CVE-2026-41088 through Windows Update or WSUS, and conduct post-patch validation to ensure kernel driver functionality remains intact.

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 21h2Operating system
Affected:< 10.0.19044.7291
Windows 10 22h2Operating system
Affected:< 10.0.19045.7291
Windows 11 23h2Operating system
Affected:< 10.0.22631.7079
Windows 11 24h2Operating system
Affected:< 10.0.26100.8390
Windows 11 25h2Operating system
Affected:< 10.0.26200.8390
Windows 11 26h1Operating system
Affected:< 10.0.28000.2113
Windows Server 2022Operating system
Affected:< 10.0.20348.5074
Windows Server 2022 23h2Operating system
Affected:< 10.0.25398.2330

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. Check installed Windows version and build number
    Run 'winver' or 'systeminfo' and locate the OS Build number. Compare it against the affected version ranges provided.
    Affected if The build number is below 19044.7291 (Windows 10 21h2), 19045.7291 (Windows 10 22h2), 22631.7079 (Windows 11 23h2), 26100.8390 (Windows 11 24h2), 26200.8390 (Windows 11 25h2), 28000.2113 (Windows 11 26h1), 20348.5074 (Server 2022), or 25398.2330 (Server 2022 23h2)
  2. Verify afd.sys driver file version
    Navigate to C:\Windows\System32\afd.sys, right-click the file, select Properties, and check the File Version details on the Version tab.
    Affected if The afd.sys file version is older than the version bundled with the security update for this CVE
  3. Confirm driver is loaded and active
    Open Command Prompt and run 'sc query afd' to query the status of the Ancillary Function Driver service.
    Affected if The service state shows as RUNNING, indicating the driver is active and the vulnerability could be exploited

A system is affected if it runs a Windows version with a build number below the patched thresholds and has the afd.sys driver loaded, as the type confusion vulnerability exists in that driver.

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 10.0.19044.7291 / 10.0.19045.7291 / 10.0.20348.5074 or later
Fixed in 10.0.19044.729110.0.19045.729110.0.20348.5074
Interim mitigation

Apply the Microsoft security update for CVE-2026-41088 through Windows Update or WSUS, and conduct post-patch validation to ensure kernel driver functionality remains intact.

Recommended fix High confidence

Install Microsoft security updates for the respective Windows version that include the fix for CVE-2026-41088 (check Microsoft Update Catalog for the specific KB number)

  1. Check current Windows version by running 'winver' or 'systeminfo' in Command Prompt
  2. Open Windows Update by navigating to Settings > Update & Security > Windows Update
  3. Click 'Check for updates' to download and install the latest security updates
  4. If using Windows Server or managed environments, use WSUS, SCCM, or group policy to deploy the relevant KB update
  5. Restart the system after updates are installed
  6. Verify the patch was applied by checking the OS build number matches or exceeds: 10.0.19044.7291 (Win10 21h2), 10.0.19045.7291 (Win10 22h2), 10.0.22631.7079 (Win11 23h2), 10.0.26100.8390 (Win11 24h2), 10.0.26200.8390 (Win11 25h2), 10.0.28000.2113 (Win11 26h1), 10.0.20348.5074 (Server 2022), or 10.0.25398.2330 (Server 2022 23h2)
Caveat Standard Windows security update with no expected breaking changes; may require restart

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

Fix this in Windows 10 21h2 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
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $4,544.

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-2026-41088 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