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Ubuntu LinuxOperating system · Canonical

CVE-2016-2118

HIGH · 7.5 CVSS v3.1 Published 2016-04-12
Fix available
A fix is available. Upgrade to 4.2.10 / 4.3.7 or later.
See remediation →
82/100
Remediation priority · High
Remotely reachable No privileges

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
The MS-SAMR and MS-LSAD protocol implementations in Samba 3.x and 4.x before 4.2.11, 4.3.x before 4.3.8, and 4.4.x before 4.4.2 mishandle DCERPC connections, which allows man-in-the-middle attackers to perform protocol-downgrade attacks and impersonate users by modifying the client-server data stream, aka "BADLOCK."

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 confidence

Samba's MS-SAMR and MS-LSAD protocol implementations improperly handle DCERPC connections, allowing man-in-the-middle attackers to perform protocol-downgrade attacks and impersonate users by modifying client-server data streams. The vulnerability stems from insufficient validation of DCERPC session integrity.

MitigationUpgrade Samba to version 4.2.11 or later, 4.3.8 or later, or 4.4.2 or later to patch the DCERPC handling flaw. For systems that cannot be immediately upgraded, restrict network access to Samba services and enforce IPsec or TLS encryption for DCERPC communications.

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
Affected:= 12.04= 14.04= 15.10= 16.04
Debian LinuxOperating system
Affected:= 7.0= 8.0
SambaApplication
Affected:>= 3.6.0, < 4.2.10>= 4.3.0, < 4.3.7>= 4.4.0, < 4.4.1

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
High
Privileges
None
User interaction
Required
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:H/PR:N/UI:R/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. Verify Samba installation
    Run `dpkg -l | grep samba` on Debian/Ubuntu or `rpm -qa | grep samba` on RHEL-based systems to list installed Samba packages.
    Affected if Samba packages are installed and the version falls within the affected ranges (3.6.0 to 4.2.10, 4.3.0 to 4.3.7, or 4.4.0 to 4.4.1).
  2. Confirm Samba version
    Run `smbstatus --version` or `samba --version` to obtain the exact Samba version number.
    Affected if The installed version is less than 4.2.11, 4.3.8, or 4.4.2 respectively.
  3. Identify exposed DCERPC endpoints
    Check the Samba configuration file (smb.conf) for 'rpc server' settings and review which network interfaces Samba listens on. Use `net rpc service list` or inspect ports 445 and 139 for listening services.
    Affected if SAMR (Security Account Manager Remote) or LSAD (Local Security Authority) DCERPC endpoints are exposed over the network without IPsec or TLS encryption.
  4. Verify DCERPC signing enforcement
    Search smb.conf for 'client signing', 'server signing', 'require strong key', or 'seal' parameters under the [global] or specific shares. Run `testparm -v 2>/dev/null | grep -i sign` to see current signing settings.
    Affected if DCERPC session integrity validation is not enforced (signing set to 'disabled' or 'auto' rather than 'required' or 'mandatory').

A system is affected if it runs a vulnerable Samba version (3.6.0 to 4.2.10, 4.3.0 to 4.3.7, or 4.4.0 to 4.4.1) with SAMR or LSAD DCERPC services exposed on the network and without mandatory signing or encryption protections.

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.

From vendor data
Upgrade available Upgrade to 4.2.10 / 4.3.7 / 4.4.1 or later
Fixed in 4.2.104.3.74.4.1
Interim mitigation

Upgrade Samba to version 4.2.11 or later, 4.3.8 or later, or 4.4.2 or later to patch the DCERPC handling flaw. For systems that cannot be immediately upgraded, restrict network access to Samba services and enforce IPsec or TLS encryption for DCERPC communications.

Fix this in Ubuntu Linux Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing6.0 h
  • Review / QA2.0 h
20.0 hours of engineering $3,500
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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-2016-2118 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