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Ubuntu LinuxOperating system · Canonical

CVE-2017-14746

CRITICAL · 9.8 CVSS v3.1 Published 2017-11-27
Fix available
A fix is available. Upgrade to 4.5.0 / 4.5.15 or later.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges Zero-click

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
Use-after-free vulnerability in Samba 4.x before 4.7.3 allows remote attackers to execute arbitrary code via a crafted SMB1 request.

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

A use-after-free memory corruption vulnerability exists in Samba versions 4.x before 4.7.3. The flaw occurs in SMB1 request handling where memory is freed but still referenced, allowing a remote attacker to execute arbitrary code via specially crafted SMB1 packets.

MitigationUpgrade Samba to version 4.7.3 or later. If upgrading is not immediately possible, consider disabling SMB1 protocol support if not required, though this may impact legacy clients.

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:= 14.04= 16.04= 17.04= 17.10
Debian LinuxOperating system
Affected:= 8.0= 9.0
Enterprise Linux DesktopOperating system
Affected:= 6.0= 7.0
Enterprise Linux ServerOperating system
Affected:= 6.0= 7.0
Enterprise Linux WorkstationOperating system
Affected:= 6.0= 7.0
SambaApplication
Affected:>= 4.0.0, < 4.5.0>= 4.5.0, < 4.5.15>= 4.6.0, < 4.6.11>= 4.7.0, < 4.7.3

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
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/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. Identify installed Samba version
    Run 'smbstatus --version' or 'samba --version' to get the Samba version number
    Affected if Version is 4.0.0 through 4.7.2 (any 4.x version before 4.7.3)
  2. Confirm SMB1 protocol is enabled
    Check /etc/samba/smb.conf for 'min protocol' or 'max protocol' settings - if either is set to SMB1, or if no protocol restrictions exist (default allows SMB1)
    Affected if SMB1 protocol is enabled or not explicitly disabled in the Samba configuration

The environment is affected if Samba version is 4.0.0 to 4.7.2 AND SMB1 protocol support is active or allowed in the configuration.

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.

dbcve · scoped
Upgrade available Upgrade to 4.5.0 / 4.5.15 / 4.6.11 or later
Fixed in 4.5.04.5.154.6.11
Interim mitigation

Upgrade Samba to version 4.7.3 or later. If upgrading is not immediately possible, consider disabling SMB1 protocol support if not required, though this may impact legacy clients.

Recommended fix High confidence

Samba 4.7.3 or later

  1. 1. Identify the current Samba version installed: smbd --version or dpkg -l | grep samba
  2. 2. For Debian/Ubuntu systems: Run 'apt-get update' followed by 'apt-get install samba' to obtain the latest available version
  3. 3. For RHEL/CentOS systems: Run 'yum update samba' to update to the latest available version
  4. 4. Ensure the upgraded Samba version is 4.7.3 or later
  5. 5. Restart the Samba services: 'systemctl restart smbd' and 'systemctl restart nmbd'
  6. 6. Verify the vulnerable SMB1 protocol is disabled if not needed, or ensure the updated version is running
Caveat Upgrading Samba may require configuration adjustments; test in non-production environment first. SMB1 protocol is deprecated and should be disabled if not required.

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Ubuntu Linux Scoped from the published advisory
  • Consultation1.0 h
  • Implementation2.0 h
  • Testing3.0 h
  • Review / QA1.0 h
7.0 hours of engineering $1,190
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Scan for this in your stack

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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-2017-14746 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