---
title: "CVE-2018-5740\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-2018-5740?format=md
keywords: index, follow
---

# CVE-2018-5740

Publication date 9 August 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-2018-5740?format=md#impact-score)

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## Description

"deny-answer-aliases" is a little-used feature intended to help recursive
server operators protect end users against DNS rebinding attacks, a
potential method of circumventing the security model used by client
browsers. However, a defect in this feature makes it easy, when the feature
is in use, to experience an assertion failure in name.c. Affects BIND
9.7.0->9.8.8, 9.9.0->9.9.13, 9.10.0->9.10.8, 9.11.0->9.11.4,
9.12.0->9.12.2, 9.13.0->9.13.2.

## Mitigation

Disable use of "deny-answer-aliases" feature

## Status

Show unmaintained releases

| Package | Ubuntu Release | Status |
| --- | --- | --- |
| bind9 | 18.04 LTS bionic | Fixed 1:9.11.3+dfsg-1ubuntu1.2 |
| 16.04 LTS xenial | Fixed 1:9.10.3.dfsg.P4-8ubuntu1.11 |
| 14.04 LTS trusty | Fixed 1:9.9.5.dfsg-3ubuntu0.18 |

---

* [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 | None |
  | Integrity impact | None |
  | Availability impact | High |
* Scores

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

**Vector:** CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

## References

* [MITRE](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2018-5740)
* [NVD](https://nvd.nist.gov/vuln/detail/CVE-2018-5740)
* [Launchpad](https://launchpad.net/bugs/cve/CVE-2018-5740)
* [Debian](https://security-tracker.debian.org/tracker/CVE-2018-5740)

### Related Ubuntu Security Notices (USN)

+ [USN-3769-1](https://usn.ubuntu.com/USN-3769-1)
+ Bind vulnerability
+ 20 September 2018

+ [USN-3769-2](https://usn.ubuntu.com/USN-3769-2)
+ Bind vulnerability
+ 1 October 2018

### Other references

* <https://kb.isc.org/article/AA-01639/74/CVE-2018-5740>
* <https://www.cve.org/CVERecord?id=CVE-2018-5740>