CVE-2016-2126
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 version 4.0.0 up to 4.5.2 is vulnerable to privilege elevation due to incorrect handling of the PAC (Privilege Attribute Certificate) checksum. A remote, authenticated, attacker can cause the winbindd process to crash using a legitimate Kerberos ticket. A local service with access to the winbindd privileged pipe can cause winbindd to cache elevated access permissions.
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 confidenceSamba versions 4.0.0 through 4.5.2 have incorrect PAC (Privilege Attribute Certificate) checksum validation in winbindd. A remote authenticated attacker can crash winbindd using a legitimate Kerberos ticket, and more critically, a local service with access to the winbindd privileged pipe can cause winbindd to cache elevated access permissions, enabling privilege escalation.
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>= 4.0.0, < 4.3.13>= 4.4.0, < 4.4.8>= 4.5.0, < 4.5.3CVSS 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:3.1/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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Check installed Samba versionRun 'smbd --version' or 'rpm -q samba' or 'dpkg -l samba' to determine the installed Samba versionAffected if Version is >= 4.0.0 and < 4.3.13, OR >= 4.4.0 and < 4.4.8, OR >= 4.5.0 and < 4.5.3
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Verify winbindd service is activeRun 'systemctl status winbind' or 'service winbind status' to check if the winbindd daemon is runningAffected if winbindd service is running and Samba version is in the affected range
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Check Samba configuration for winbindInspect /etc/samba/smb.conf for 'idmap config' directives or 'security = domain' settings that enable winbind integrationAffected if Samba is configured to use winbind for authentication and version is affected
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Verify winbind privileged pipe accessCheck file permissions on /var/lib/samba/winbindd_privileged/ or run 'ls -la /var/lib/samba/winbindd_privileged/' to see who has accessAffected if Non-root users or services have access to the winbindd privileged pipe and version is affected
System is affected if Samba version is 4.0.0 through 4.5.2 and winbindd is actively used for domain authentication or user mapping.
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 data4.3.134.4.84.5.3
Upgrade Samba to version 4.5.3 or later to obtain the patched version. Additionally, restrict access to the winbindd privileged pipe to prevent local privilege escalation while planning the upgrade.
- Consultation3.0 h
- Implementation6.0 h
- Testing4.0 h
- Review / QA2.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2016-2126 — 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-2016-2126 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
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