Ubuntu LinuxOperating system · Canonical
CVE-2019-12436
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 · uneditedSamba 4.10.x before 4.10.5 has a NULL pointer dereference, leading to an AD DC LDAP server Denial of Service. This is related to an attacker using the paged search control. The attacker must have directory read access in order to attempt an exploit.
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 confidenceA NULL pointer dereference vulnerability in Samba 4.10.x before 4.10.5 allows an authenticated attacker with directory read access to trigger a denial of service in the AD DC LDAP server by exploiting the paged search control.
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
Ubuntu LinuxOperating system
= 19.04>= 4.10.0, < 4.10.5CVSS 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
- Low
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- None
- Availability
- High
CVSS:3.0/AV:N/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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Identify Samba versionRun 'smbd --version' or 'samba --version' to obtain the installed Samba versionAffected if The version is 4.10.0 through 4.10.4 (versions >= 4.10.0 and < 4.10.5)
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Confirm Samba AD DC is in useCheck if the server is running as an Active Directory Domain Controller by running 'samba-tool domain info 127.0.0.1' or checking for 'server role = active directory domain controller' in smb.confAffected if The server is configured as an AD DC and the Samba version falls within the affected range
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Verify LDAP directory read access policiesReview LDAP access controls via 'samba-tool ldapcmp' or by examining the AD DC ACLs for the LDAP directory partitionAffected if Non-trusted or low-privilege users have been granted directory read access to the LDAP database
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Check if paged search is accessibleAttempt an authenticated LDAP paged search query using ldapsearch with the '-E pr=100' paged results control flag to confirm the feature is accessibleAffected if The paged search control responds without error, indicating the LDAP server is processing such requests
The environment is affected if Samba version 4.10.0 through 4.10.4 is running as an AD DC and allows authenticated users with directory read access to perform LDAP paged search queries.
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 data4.10.5
Upgrade Samba to version 4.10.5 or later. As a compensating control, restrict LDAP directory read access to trusted users only until the upgrade can be performed.
Fix this in Ubuntu Linux
Scoped from the published advisory
- Consultation3.0 h
- Implementation4.0 h
- Testing3.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $3,408.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2019-12436 — 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-2019-12436 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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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.
- 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
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