---
title: "CVE-2018-5738\n    | Ubuntu"
description: Ubuntu is an open source software operating system that runs from the
  desktop, to the cloud, to all your internet connected things.
url: https://ubuntu.com/security/CVE-2018-5738?format=md
keywords: index, follow
---

# CVE-2018-5738

Publication date 12 June 2018

Last updated 25 August 2025

---

Ubuntu priority

**Medium**

[Why this priority?](https://ubuntu.com/security/cves/about#priority )

## Cvss 3 Severity Score

**7.5 · High**

[Score breakdown](https://ubuntu.com/security/CVE-2018-5738?format=md#impact-score)

Toggle side navigation

## Description

Change #4777 (introduced in October 2017) introduced an unforeseen issue in
releases which were issued after that date, affecting which clients are
permitted to make recursive queries to a BIND nameserver. The intended (and
documented) behavior is that if an operator has not specified a value for
the "allow-recursion" setting, it SHOULD default to one of the following:
none, if "recursion no;" is set in named.conf; a value inherited from the
"allow-query-cache" or "allow-query" settings IF "recursion yes;" (the
default for that setting) AND match lists are explicitly set for
"allow-query-cache" or "allow-query" (see the BIND9 Administrative
Reference Manual section 6.2 for more details); or the intended default of
"allow-recursion {localhost; localnets;};" if "recursion yes;" is in effect
and no values are explicitly set for "allow-query-cache" or "allow-query".
However, because of the regression introduced by change #4777, it is
possible when "recursion yes;" is in effect and no match list values are
provided for "allow-query-cache" or "allow-query" for the setting of
"allow-recursion" to inherit a setting of all hosts from the "allow-query"
setting default, improperly permitting recursion to all clients. Affects
BIND 9.9.12, 9.10.7, 9.11.3, 9.12.0->9.12.1-P2, the development release
9.13.0, and also releases 9.9.12-S1, 9.10.7-S1, 9.11.3-S1, and 9.11.3-S2
from BIND 9 Supported Preview Edition.

## Status

Show unmaintained releases

| Package | Ubuntu Release | Status |
| --- | --- | --- |
| bind9 | 18.04 LTS bionic | Fixed 1:9.11.3+dfsg-1ubuntu1.1 |
| 17.10 artful | Not affected |
| 16.04 LTS xenial | Not affected |
| 14.04 LTS trusty | Not affected |

---

* [How can I get the fixes?](https://ubuntu.com/security/cves/about#security)
* [What do statuses mean?](https://ubuntu.com/security/cves/about#statuses)

## Severity score breakdown

CVSS version:
CVSS v3.0

**Base score**

7.5 · High

* Base metrics

  | Parameter | Value |
  | --- | --- |
  | Attack vector | Network |
  | Attack complexity | Low |
  | Privileges required | None |
  | User interaction | None |
  | Scope | Unchanged |
  | Confidentiality impact | High |
  | Integrity impact | None |
  | Availability impact | None |
* Scores

  | Parameter | Value |
  | --- | --- |
  | Base score | 7.5 · High |
  | Exploitability score | - |
  | Impact score | - |

**Vector:** CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

## References

* [MITRE](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2018-5738)
* [NVD](https://nvd.nist.gov/vuln/detail/CVE-2018-5738)
* [Launchpad](https://launchpad.net/bugs/cve/CVE-2018-5738)
* [Debian](https://security-tracker.debian.org/tracker/CVE-2018-5738)

### Related Ubuntu Security Notices (USN)

+ [USN-3683-1](https://usn.ubuntu.com/USN-3683-1)
+ Bind vulnerability
+ 13 June 2018

### Other references

* <https://kb.isc.org/article/AA-01616/0/CVE-2018-5738>
* <https://www.cve.org/CVERecord?id=CVE-2018-5738>