---
title: "CVE-2017-9109\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-2017-9109?format=md
keywords: index, follow
---

# CVE-2017-9109

Publication date 18 June 2020

Last updated 26 August 2025

---

Ubuntu priority

**Medium**

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

## Cvss 3 Severity Score

**9.8 · Critical**

[Score breakdown](https://ubuntu.com/security/CVE-2017-9109?format=md#impact-score)

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## Description

An issue was discovered in adns before 1.5.2. It fails to ignore apparent
answers before the first RR that was found the first time. when this is
fixed, the second answer scan finds the same RRs at the first. Otherwise,
adns can be confused by interleaving answers for the CNAME target, with the
CNAME itself. In that case the answer data structure (on the heap) can be
overrun. With this fixed, it prefers to look only at the answer RRs which
come after the CNAME, which is at least arguably correct.

## Status

Show unmaintained releases

| Package | Ubuntu Release | Status |
| --- | --- | --- |
| adns | 26.04 LTS resolute | Not affected |
| 25.10 questing | Not affected |
| 25.04 plucky | Not affected |
| 24.10 oracular | Not affected |
| 24.04 LTS noble | Not affected |
| 23.10 mantic | Not affected |
| 23.04 lunar | Not affected |
| 22.10 kinetic | Not affected |
| 22.04 LTS jammy | Not affected |
| 21.10 impish | Not affected |
| 21.04 hirsute | Not affected |
| 20.10 groovy | Not affected |
| 20.04 LTS focal | Vulnerable |
| 19.10 eoan | Ignored end of life |
| 18.04 LTS bionic | Vulnerable |
| 16.04 LTS xenial | Vulnerable |
| 14.04 LTS trusty | Not in release |

---

* [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**

9.8 · Critical

* Base metrics

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

  | Parameter | Value |
  | --- | --- |
  | Base score | 9.8 · Critical |
  | Exploitability score | - |
  | Impact score | - |

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

## References

* [MITRE](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2017-9109)
* [NVD](https://nvd.nist.gov/vuln/detail/CVE-2017-9109)
* [Launchpad](https://launchpad.net/bugs/cve/CVE-2017-9109)
* [Debian](https://security-tracker.debian.org/tracker/CVE-2017-9109)

### Other references

* <http://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?p=adns.git;a=commit;h=fcf2b4e1faf22accb6184cca595aaee602839868>
* <https://www.cve.org/CVERecord?id=CVE-2017-9109>