CVE-2026-3238
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 · uneditedA flaw was found in Samba’s WINS server component when running as an Active Directory Domain Controller. The WINS protocol handlers for certain request types did not properly validate incoming packets, allowing an unauthenticated remote attacker to trigger a NULL pointer dereference and crash the WINS service using specially crafted UDP packets.
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 · high confidenceThe WINS server component in Samba when running as an Active Directory Domain Controller lacks proper validation on incoming packets for certain request types. An unauthenticated remote attacker can send specially crafted UDP packets to trigger a NULL pointer dereference, causing the WINS service to crash.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
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
- Network
- Complexity
- Low
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- None
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:N/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 Samba versionRun 'samba --version' or 'smbd --version' to determine the installed Samba versionAffected if The installed version is within a range that contains this vulnerability (compare against official Samba security advisories)
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Verify Samba is running as Active Directory Domain ControllerInspect /etc/samba/smb.conf and look for 'server role = active directory domain controller' or check process list for 'samba' processes running as DCAffected if Samba is configured and running as an Active Directory Domain Controller
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Confirm WINS server component is enabledCheck smb.conf for 'wins support = yes' or 'wins server = <IP>' and verify the nmbd process is running via 'ps aux | grep nmbd'Affected if WINS support is enabled in the configuration and the WINS server (nmbd) is running
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Assess network exposure of WINS portsRun 'netstat -ulpn | grep -E ':(137|138)' or 'ss -ulpn | grep -E ':(137|138)' to check if UDP ports 137 and 138 are listening, and review firewall rulesAffected if UDP ports 137/138 are exposed to untrusted or external networks
You are affected if Samba is running as an AD DC with WINS server enabled and UDP ports 137/138 are accessible to untrusted remote attackers.
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.
From vendor dataApply the Samba security update to address the input validation flaw. If unavailable, disable the WINS service or restrict access to UDP port 137 from untrusted network sources.
- Consultation2.0 h
- Implementation2.0 h
- Testing2.0 h
- Review / QA1.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,984.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-3238 — 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-2026-3238 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
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