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FedoraOperating system · Fedoraproject

CVE-2019-14861

MEDIUM · 5.3 CVSS v3.1 Published 2019-12-10
Fix available
A fix is available. Upgrade to 4.9.17 / 4.10.11 or later.
See remediation →
59/100
Remediation priority · Elevated
Remotely reachable 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
All Samba versions 4.x.x before 4.9.17, 4.10.x before 4.10.11 and 4.11.x before 4.11.3 have an issue, where the (poorly named) dnsserver RPC pipe provides administrative facilities to modify DNS records and zones. Samba, when acting as an AD DC, stores DNS records in LDAP. In AD, the default permissions on the DNS partition allow creation of new records by authenticated users. This is used for example to allow machines to self-register in DNS. If a DNS record was created that case-insensitively matched the name of the zone, the ldb_qsort() and dns_name_compare() routines could be confused into reading memory prior to the list of DNS entries when responding to DnssrvEnumRecords() or DnssrvEnumRecords2() and so following invalid memory as a pointer.

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

All Samba versions 4.9.x before 4.9.17, 4.10.x before 4.10.11, and 4.11.x before 4.11.3 contain a memory read vulnerability in the dnsserver RPC pipe. When a DNS record is created that case-insensitively matches the zone name, the ldb_qsort() and dns_name_compare() routines miscalculate memory offsets, causing them to read memory prior to the DNS entries list and follow invalid memory as a pointer during DnssrvEnumRecords() or DnssrvEnumRecords2() calls.

MitigationUpgrade Samba to version 4.9.17, 4.10.11, or 4.11.3 or later. Alternatively, restrict the ability to create DNS records in the AD DNS partition to only required service accounts, and monitor for DNS records that match zone names.

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
FedoraOperating system
Affected:= 30= 31
Ubuntu LinuxOperating system
Affected:= 14.04= 16.04= 18.04= 19.04= 19.10
Debian LinuxOperating system
Affected:= 9.0
SambaApplication
Affected:>= 4.0.0, < 4.9.17>= 4.10.0, < 4.10.11>= 4.11.0, < 4.11.3
LeapOperating system
Affected:= 15.1

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
Low
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:H/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 checks

Work through these to decide whether this CVE applies to you.

  1. Check installed Samba version
    Run 'samba --version' or 'rpm -q samba' (RHEL/Fedora) or 'dpkg -l samba' (Debian/Ubuntu) to retrieve the installed Samba version
    Affected if Version is below 4.9.17, between 4.10.0-4.10.10, or between 4.11.0-4.11.2
  2. Confirm Samba AD DC role
    Check if Samba is configured as an Active Directory Domain Controller by examining the 'server role' in smb.conf (typically located at /etc/samba/smb.conf) or by running 'samba-tool domain info'
    Affected if Samba is running as an AD Domain Controller (server role = active directory domain controller)
  3. Verify DNS server is enabled
    Check if the dns service is listed in the 'server services' parameter in smb.conf, or verify the dnsserver RPC pipe is accessible via 'smbclient -L localhost -U admin' and look for dnsserver pipe
    Affected if DNS server role is enabled in Samba configuration (dnsserver RPC pipe is present)
  4. Check for DNS records matching zone names
    Query DNS records using 'samba-tool dns query' or ldapsearch for any records where the record name case-insensitively matches the zone name
    Affected if A DNS record exists with a name that matches its zone name (case-insensitive), which triggers the vulnerable code path

Samba is vulnerable if version is 4.9.x < 4.9.17, 4.10.x < 4.10.11, or 4.11.x < 4.11.3 AND Samba is running as an AD DC with DNS server enabled AND a DNS record matching the zone name exists

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 4.9.17 / 4.10.11 / 4.11.3 or later
Fixed in 4.9.174.10.114.11.3
Interim mitigation

Upgrade Samba to version 4.9.17, 4.10.11, or 4.11.3 or later. Alternatively, restrict the ability to create DNS records in the AD DNS partition to only required service accounts, and monitor for DNS records that match zone names.

Fix this in Fedora Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing6.0 h
  • Review / QA2.0 h
14.0 hours of engineering $2,380
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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-2019-14861 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