CVE-2018-5741
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 · uneditedTo provide fine-grained controls over the ability to use Dynamic DNS (DDNS) to update records in a zone, BIND 9 provides a feature called update-policy. Various rules can be configured to limit the types of updates that can be performed by a client, depending on the key used when sending the update request. Unfortunately, some rule types were not initially documented, and when documentation for them was added to the Administrator Reference Manual (ARM) in change #3112, the language that was added to the ARM at that time incorrectly described the behavior of two rule types, krb5-subdomain and ms-subdomain. This incorrect documentation could mislead operators into believing that policies they had configured were more restrictive than they actually were. This affects BIND versions prior to BIND 9.11.5 and BIND 9.12.3.
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 confidenceThe BIND 9 Administrator Reference Manual (ARM) incorrectly documented the behavior of two update-policy rule types (krb5-subdomain and ms-subdomain) used for fine-grained control over Dynamic DNS updates. This documentation error (added in change #3112) could cause operators to believe their DDNS update restrictions were more restrictive than they actually were, potentially allowing unauthorized record updates.
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< 9.11.5>= 9.12.0, < 9.12.3CVSS 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
- High
- Availability
- None
CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N
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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Determine installed BIND versionRun 'named -v' or 'named -V' to display the BIND version informationAffected if Version is shown as less than 9.11.5 or >= 9.12.0 but less than 9.12.3
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Locate BIND configuration fileFind the named.conf file, typically in /etc/named.conf, /etc/bind/named.conf, or as specified in the named startup scriptAffected if Configuration file exists and contains update-policy rules
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Check for affected update-policy rulesSearch the configuration file for 'update-policy' statements and examine whether 'krb5-subdomain' or 'ms-subdomain' rule types are definedAffected if Any update-policy rule uses krb5-subdomain or ms-subdomain as the type
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Verify documentation mismatch existsCompare the documented behavior of krb5-subdomain and ms-subdomain in the ARM against the actual BIND behavior - the rules grant broader update permissions to subdomains than the documentation statedAffected if The update-policy configuration uses krb5-subdomain or ms-subdomain in a version that falls within the affected range, meaning the operator may have relied on incomplete documentation to restrict updates
The environment is affected if BIND version is less than 9.11.5 or between 9.12.0 and 9.12.3 AND the configuration uses update-policy with krb5-subdomain or ms-subdomain rules, potentially allowing unauthorized DDNS updates beyond what operators intended.
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 data9.11.59.12.3
Verify update-policy configurations using krb5-subdomain and ms-subdomain rules against actual BIND 9 behavior, and upgrade to BIND 9.11.5 or 9.12.3 where the documentation was corrected.
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- Implementation1.0 h
- Testing2.0 h
- Review / QA1.0 h
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Free · runs locallyCheck whether your project pulls in CVE-2018-5741 — 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-2018-5741 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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- Version or environment caveats, and links to real fixes
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