dbcve.org
Windows 10 1607Operating system · Microsoft

CVE-2026-34346

MEDIUM · 5.5 CVSS v3.1 Published 2026-07-14
Fix available
A fix is available. Upgrade to 10.0.14393.9339 / 10.0.17763.9020 or later.
See remediation →
57/100
Remediation priority · Elevated
Zero-click 5 weeks old

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
Cleartext transmission of sensitive information in Windows Ancillary Function Driver for WinSock allows an authorized attacker to disclose information locally.

In the news

Third-party coverage
Trending covered by 1 outlet this week · latest 1w 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 cleartext transmission vulnerability exists in the Windows Ancillary Function Driver for WinSock that allows a locally authorized attacker to intercept sensitive information being transmitted between system components. The driver fails to encrypt sensitive data during local communication, enabling confidentiality breach.

MitigationApply Microsoft security updates for the Windows Ancillary Function Driver. As a defense-in-depth measure, restrict local administrative privileges and monitor for unusual access patterns to system driver communications.

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:< 10.0.14393.9339
Windows 10 1809Operating system
Affected:< 10.0.17763.9020
Windows 10 21h2Operating system
Affected:< 10.0.19044.7548
Windows 10 22h2Operating system
Affected:< 10.0.19045.7548
Windows 11 23h2Operating system
Affected:< 10.0.22631.7376
Windows 11 24h2Operating system
Affected:< 10.0.26100.8875
Windows 11 25h2Operating system
Affected:< 10.0.26200.8875
Windows 11 26h1Operating system
Affected:< 10.0.28000.2269

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
None
Availability
None

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N

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. Locate the Afd.sys driver file
    Open File Explorer and navigate to C:\Windows\System32\drivers\afd.sys, or run 'dir C:\Windows\System32\drivers\afd.sys' in Command Prompt
    Affected if The file does not exist (the driver is not present on the system)
  2. Obtain the Afd.sys file version
    Right-click afd.sys, select Properties, then view the Details tab for the File Version. Alternatively, run 'powershell (Get-Item 'C:\Windows\System32\drivers\afd.sys').VersionInfo.FileVersion' in Command Prompt
    Affected if The version displayed is lower than the fixed versions in the affected ranges (e.g., below 10.0.14393.9339 for Windows 10 1607, below 10.0.17763.9020 for Windows 10 1809, etc.)
  3. Confirm Windows version to match correct affected range
    Run 'winver' in Command Prompt or check System Properties to identify the exact Windows build (e.g., 1607, 1809, 21h2, 22h2, 23h2, 24h2, 25h2, or 26h1)
    Affected if The installed Windows build matches one of the affected versions AND the Afd.sys version is below the corresponding fixed version for that build
  4. Verify the driver is loaded and active
    Run 'sc query afd' in Command Prompt or open Services app and check if the 'Afd' service exists and is running
    Affected if The driver service is present and running on a vulnerable Windows version with an outdated driver file version

A user is affected if they are running any of the listed Windows versions AND the Afd.sys file version is below the specified cutoff for that Windows build, since the driver then transmits sensitive data without encryption during local communication.

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 10.0.14393.9339 / 10.0.17763.9020 / 10.0.19044.7548 or later
Fixed in 10.0.14393.933910.0.17763.902010.0.19044.7548
Interim mitigation

Apply Microsoft security updates for the Windows Ancillary Function Driver. As a defense-in-depth measure, restrict local administrative privileges and monitor for unusual access patterns to system driver communications.

Recommended fix High confidence

Windows 10 1607 to build 10.0.14393.9339 or later | Windows 10 1809 to build 10.0.17763.9020 or later | Windows 10 21h2 to build 10.0.19044.7548 or later | Windows 10 22h2 to build 10.0.19045.7548 or later | Windows 11 23h2 to build 10.0.22631.7376 or later | Windows 11 24h2 to build 10.0.26100.8875

  1. Identify the current Windows version and build number by running 'winver' or 'systeminfo' in Command Prompt
  2. Determine which Windows 10 or 11 version and build is currently installed
  3. Upgrade to or install a Windows version that meets or exceeds the fixed build number for your release channel: For Windows 10 1607 upgrade to 10.0.14393.9339 or later; For Windows 10 1809 upgrade to 10.0.17763.9020 or later; For Windows 10 21h2 upgrade to 10.0.19044.7548 or later; For Windows 10 22h2 upgrade to 10.0.19045.7548 or later; For Windows 11 23h2 upgrade to 10.0.22631.7376 or later; For
  4. Apply the upgrade via Windows Update, or download the appropriate ISO from Microsoft's Volume Licensing Service Center or the Microsoft Update Catalog
  5. After upgrading, verify the new build number matches or exceeds the fixed version using 'winver'
Caveat Standard Windows update compatibility applies; major version upgrades may require application compatibility testing

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-2026-34346 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