CVE-2026-34339
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 · uneditedNull pointer dereference in Windows LDAP - Lightweight Directory Access Protocol allows an authorized attacker to deny service 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 confidenceA null pointer dereference vulnerability exists in Windows LDAP (Lightweight Directory Access Protocol) that allows an authorized local attacker to cause a denial of service by crashing the LDAP service or related system processes.
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< 10.0.14393.9140< 10.0.17763.8755< 10.0.19044.7291< 10.0.19045.7291< 10.0.22631.7079< 10.0.26100.8390< 10.0.26200.8390< 10.0.28000.2113CVSS 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
- None
- Integrity
- None
- Availability
- High
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/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 checksWork through these to decide whether this CVE applies to you.
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Check installed Windows versionRun 'winver' or 'systeminfo | findstr /B /C:"OS Name" /C:"OS Version"' to see the exact Windows build numberAffected if The build number is less than the version thresholds listed in the affected products (e.g., below 10.0.14393.9140 for Windows 10 1607, below 10.0.17763.8755 for Windows 10 1809, etc.)
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Verify LDAP service statusOpen Services console (services.msc) and locate the 'LDAP' service, or run 'Get-Service *LDAP*' in PowerShellAffected if The LDAP service exists and is running on the system
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Confirm Windows Edition is affectedRun 'winver' or check System Properties to confirm the Windows edition (Home, Pro, Enterprise) matches one of the affected versionsAffected if The system runs a Windows 10 or Windows 11 edition listed in the affected products with a version below the fixed builds
A system is affected if it runs any of the listed Windows versions with a build number below the fixed thresholds and has the LDAP service present and enabled.
Generated from the published advisory. Verify against your own configuration.
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 · scoped10.0.14393.914010.0.17763.875510.0.19044.7291
Apply Microsoft security updates for Windows when available. Ensure LDAP services are not exposed to untrusted networks and follow least-privilege principles for local user accounts.
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
- Open Settings > Update & Security > Windows Update
- Click 'Check for updates' to download and install the latest security updates
- Restart the system when prompted to complete the installation
- Verify the update was installed by running 'winver' command and confirming the build number matches or exceeds the fixed version for your Windows edition
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation2.0 h
- Implementation2.0 h
- Testing3.0 h
- Review / QA1.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-34339 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2026-34339 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- 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