dbcve.org
Windows 10 1607Operating system · Microsoft

CVE-2026-33099

HIGH · 7.0 CVSS v3.1 Published 2026-04-14
Fix available
A fix is available. Upgrade to 10.0.14393.9060 / 10.0.17763.8644 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
Use after free 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

Use-after-free vulnerability in the Windows Ancillary Function Driver for WinSock (afd.sys) allows a local authorized attacker to elevate privileges to SYSTEM level by manipulating kernel memory after a buffer is freed.

MitigationApply Microsoft security updates for this vulnerability as soon as possible; prioritize patching systems with local user access where privilege escalation risk exists.

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:< 10.0.14393.9060
Windows 10 1809Operating system
Affected:< 10.0.17763.8644
Windows 10 21h2Operating system
Affected:< 10.0.19044.7184
Windows 10 22h2Operating system
Affected:< 10.0.19045.7184
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 Server 2012Operating system
Affected:all versions= r2

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. Identify your Windows version
    Run 'winver' from the command prompt or check System Properties. Alternatively, run 'systeminfo | findstr /B /C:"OS Name" /C:"OS Version"' to get the exact build number.
    Affected if The displayed version falls within any of these ranges: Windows 10 1607 (build < 14393.9060), Windows 10 1809 (build < 17763.8644), Windows 10 21h2 (build < 19044.7184), Windows 10 22h2 (build < 19045.7184), Windows 11 23h2 (build < 22631.6936), Windows 11 24h2 (build < 26100.8246), Windows 11 25h2
  2. Confirm AFD.sys presence
    Verify that the file C:\Windows\System32\drivers\afd.sys exists on the system. This driver is part of the Windows networking stack and should be present.
    Affected if The file exists, which is required for the vulnerability to be present. All unpatched systems with this driver are potentially affected.
  3. Check AFD.sys file version (optional)
    Right-click afd.sys in C:\Windows\System32\drivers\, select Properties, then Details. Alternatively, run 'powershell "(Get-Item C:\Windows\System32\drivers\afd.sys).VersionInfo" to retrieve the file version.
    Affected if The file version is lower than the patched version corresponding to your Windows build. Compare your version against the Microsoft Security Update guidance for this CVE.

You are affected if your Windows version or AFD.sys build number is below the patched thresholds listed for your specific 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 10.0.14393.9060 / 10.0.17763.8644 / 10.0.19044.7184 or later
Fixed in 10.0.14393.906010.0.17763.864410.0.19044.7184
Interim mitigation

Apply Microsoft security updates for this vulnerability as soon as possible; prioritize patching systems with local user access where privilege escalation risk exists.

Recommended fix High confidence

Upgrade to the specified build numbers for each Windows version (10.0.14393.9060+, 10.0.17763.8644+, 10.0.19044.7184+, 10.0.19045.7184+, 10.0.22631.6936+, 10.0.26100.8246+, 10.0.26200.8246+); migrate from Windows Server 2012/2012 R2 to supported Windows Server versions

  1. Identify the current Windows version by running 'winver' or 'systeminfo' in Command Prompt
  2. For Windows 10 1607 systems: Upgrade to Windows 10 version 1607 build 10.0.14393.9060 or later
  3. For Windows 10 1809 systems: Upgrade to Windows 10 version 1809 build 10.0.17763.8644 or later
  4. For Windows 10 21h2 systems: Upgrade to Windows 10 version 21h2 build 10.0.19044.7184 or later
  5. For Windows 10 22h2 systems: Upgrade to Windows 10 version 22h2 build 10.0.19045.7184 or later
  6. For Windows 11 23h2 systems: Upgrade to Windows 11 version 23h2 build 10.0.22631.6936 or later
  7. For Windows 11 24h2 systems: Upgrade to Windows 11 version 24h2 build 10.0.26100.8246 or later
  8. For Windows 11 25h2 systems: Upgrade to Windows 11 version 25h2 build 10.0.26200.8246 or later
Caveat Windows Server 2012/2012 R2 is end-of-life with no security updates available - requires OS migration; ensure application compatibility before upgrading production systems

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
  • Implementation4.0 h
  • Testing3.0 h
  • Review / QA1.0 h
10.0 hours of engineering $1,750
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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-2026-33099 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