dbcve.org
Windows 10 1607Operating system · Microsoft

CVE-2026-34345

HIGH · 7.0 CVSS v3.1 Published 2026-05-12
Fix available
A fix is available. Upgrade to 10.0.14393.9140 / 10.0.17763.8755 or later.
See remediation →
72/100
Remediation priority · Elevated
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 exists in the Windows Ancillary Function Driver for WinSock (AFD.sys), a kernel-mode driver that handles Winsock operations. The flaw allows an authorized local attacker to exploit improper type handling to elevate privileges from a standard user to SYSTEM level. This is a kernel-level privilege escalation vulnerability affecting Windows systems.

MitigationApply the relevant Microsoft security update for this vulnerability through Windows Update or manual patch deployment. Verify that endpoint protection and least-privilege principles are enforced to limit local attack surface.

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:< 10.0.14393.9140
Windows 10 1809Operating system
Affected:< 10.0.17763.8755
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

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
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:L/AC:H/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 Windows build number
    Run 'winver' or 'systeminfo | findstr /B /C:"OS Name" /C:"OS Version"' in Command Prompt to get the exact build number
    Affected if The build number falls below the fixed version for your Windows release (e.g., 10.0.14393.9140 for Windows 10 1607, 10.0.17763.8755 for Windows 10 1809, etc.)
  2. Verify Windows edition
    Run 'winver' to confirm whether you are on Windows 10 1607, 1809, 21h2, 22h2, or Windows 11 23h2, 24h2, 25h2, or 26h1
    Affected if The system runs any of the affected editions listed in the version ranges and the build is below the corresponding threshold
  3. Check AFD.sys file version
    Locate AFD.sys in C:\Windows\System32\drivers\, right-click and select Properties, then view the File Version details, or run 'powershell (Get-Item C:\Windows\System32\drivers\AFD.sys).VersionInfo'
    Affected if The file version is lower than the build number threshold for your Windows version (the driver version typically matches the OS build)
  4. Confirm standard user access exists
    This vulnerability requires a local authenticated user account. Verify the accounts on the system by running 'net user' in Command Prompt
    Affected if Standard non-privileged local or domain users exist on the system, making them potential attackers if the patch is not applied

The system is affected if it runs any of the listed Windows 10 or 11 versions with a build number lower than the specified threshold, and the AFD.sys driver matches that vulnerable build range.

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 10.0.14393.9140 / 10.0.17763.8755 / 10.0.19044.7291 or later
Fixed in 10.0.14393.914010.0.17763.875510.0.19044.7291
Interim mitigation

Apply the relevant Microsoft security update for this vulnerability through Windows Update or manual patch deployment. Verify that endpoint protection and least-privilege principles are enforced to limit local attack surface.

Recommended fix High confidence

Windows 10 1607: 10.0.14393.9140 | Windows 10 1809: 10.0.17763.8755 | Windows 10 21h2: 10.0.19044.7291 | Windows 10 22h2: 10.0.19045.7291 | Windows 11 23h2: 10.0.22631.7079 | Windows 11 24h2: 10.0.26100.8390 | Windows 11 25h2: 10.0.26200.8390 | Windows 11 26h1: 10.0.28000.2113

  1. 1. Identify the current Windows version by opening Settings > System > About or running 'winver' in the command prompt
  2. 2. Determine which build version is currently installed (e.g., for Windows 10 22h2, check if below 10.0.19045.7291)
  3. 3. Open Windows Update by going to Settings > Update & Security > Windows Update
  4. 4. Click 'Check for updates' to download and install the latest security updates
  5. 5. After installation, restart the system when prompted
  6. 6. Verify the update was successful by checking the build number matches or exceeds the fixed version for your Windows release
  7. 7. Alternatively, download the specific security update from the Microsoft Update Catalog matching your Windows version (search for the CVE patch date)
Caveat Standard Windows cumulative update - minimal risk; may require restart

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

Fix this in Windows 10 1607 Scoped from the published advisory
  • Consultation2.0 h
  • Implementation1.0 h
  • Testing2.0 h
  • Review / QA1.0 h
6.0 hours of engineering $1,060
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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-2026-34345 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