To 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.
Advisories
Source ID Title
EUVD EUVD EUVD-2018-17510 To 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.
Fixes

Solution

At the time of public disclosure, ISC is not providing any code changing the behavior of the update-policy feature. While we believe that there are a few operators out there who are relying on the strictest interpretation permitted by the erroneous documentation, we have to balance that against changing the behavior of features in stable branches of BIND, including the 9.11 branch which is meant to be a feature-complete Extended Support Version of BIND 9. As a compromise between these conflicting priorities, we have decided that our best course of action is to disclose the error but leave the existing behavior of the krb5-subdomain and ms-subdomain policies as they are (while correcting the erroneous documentation). In maintenance releases issued during or after October 2018, the name field for ms-subdomain and krb5-subdomain will be corrected so that names lower than "." can be configured, and two new rule types will be added, krb5-selfsub and ms-selfsub, analogous to the existing selfsub rule type, which implement the behavior that was formerly described in the documentation for krb5-subdomain and ms-subdomain: restricting updates to names at or below the machine name encoded in the client's Windows or Kerberos principal.


Workaround

To limit updates to a subset of a zone -- for example, "sub.example.com" -- create a new "sub.example.com" child zone beneath "example.com", and set the desired update-policy in the child zone rather than the parent.

History

Sun, 13 Jul 2025 13:45:00 +0000

Type Values Removed Values Added
Metrics epss

{'score': 0.0052}

epss

{'score': 0.00379}


Sat, 12 Jul 2025 13:45:00 +0000

Type Values Removed Values Added
Metrics epss

{'score': 0.00495}

epss

{'score': 0.0052}


cve-icon MITRE

Status: PUBLISHED

Assigner: isc

Published:

Updated: 2024-09-17T02:26:39.095Z

Reserved: 2018-01-17T00:00:00

Link: CVE-2018-5741

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Modified

Published: 2019-01-16T20:29:01.050

Modified: 2024-11-21T04:09:17.707

Link: CVE-2018-5741

cve-icon Redhat

Severity : Moderate

Publid Date: 2018-09-20T00:00:00Z

Links: CVE-2018-5741 - Bugzilla

cve-icon OpenCVE Enrichment

No data.