---
title: "CVE-2017-13721\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-2017-13721?format=md
keywords: index, follow
---

# CVE-2017-13721

Publication date 9 October 2017

Last updated 25 August 2025

---

Ubuntu priority

**Low**

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

## Cvss 3 Severity Score

**4.7 · Medium**

[Score breakdown](https://ubuntu.com/security/CVE-2017-13721?format=md#impact-score)

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## Description

In X.Org Server (aka xserver and xorg-server) before 1.19.4, an attacker
authenticated to an X server with the X shared memory extension enabled can
cause aborts of the X server or replace shared memory segments of other X
clients in the same session.

## Status

Show unmaintained releases

| Package | Ubuntu Release | Status |
| --- | --- | --- |
| xorg | 17.04 zesty | Not affected |
| 16.04 LTS xenial | Not affected |
| 14.04 LTS trusty | Not in release |
| xorg-hwe-16.04 | 17.04 zesty | Not in release |
| 16.04 LTS xenial | Not affected |
| 14.04 LTS trusty | Not in release |
| xorg-server | 17.04 zesty | Fixed 2:1.19.3-1ubuntu1.2 |
| 16.04 LTS xenial | Fixed 2:1.18.4-0ubuntu0.6 |
| 14.04 LTS trusty | Fixed 2:1.15.1-0ubuntu2.10 |
| xorg-server-hwe-16.04 | 17.04 zesty | Not in release |
| 16.04 LTS xenial | Fixed 2:1.19.3-1ubuntu1~16.04.3 |
| 14.04 LTS trusty | Not in release |
| xorg-server-lts-utopic | 17.04 zesty | Not in release |
| 16.04 LTS xenial | Not in release |
| 14.04 LTS trusty | Not in release |
| xorg-server-lts-vivid | 17.04 zesty | Not in release |
| 16.04 LTS xenial | Not in release |
| 14.04 LTS trusty | Not in release |
| xorg-server-lts-wily | 17.04 zesty | Not in release |
| 16.04 LTS xenial | Not in release |
| 14.04 LTS trusty | Not in release |
| xorg-server-lts-xenial | 17.04 zesty | Not in release |
| 16.04 LTS xenial | Not in release |
| 14.04 LTS trusty | Fixed 2:1.18.3-1ubuntu2.3~trusty3 |

---

* [How can I get the fixes?](https://ubuntu.com/security/cves/about#security)
* [What do statuses mean?](https://ubuntu.com/security/cves/about#statuses)
* [Patch details](https://ubuntu.com/security/CVE-2017-13721?format=md#patch-details)

### Patch details

For informational purposes only. We recommend not to cherry-pick updates. [How can I get the fixes?](https://ubuntu.com/security/cves/about#security)

| Package | Patch details |
| --- | --- |
| xorg-server | * Upstream:   [?id=b95](https://cgit.freedesktop.org/xorg/xserver/commit/?id=b95f25af141d33a65f6f821ea9c003f66a01e1f1) |

## Severity score breakdown

CVSS version:
CVSS v3.0

**Base score**

4.7 · Medium

* Base metrics

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

  | Parameter | Value |
  | --- | --- |
  | Base score | 4.7 · Medium |
  | Exploitability score | - |
  | Impact score | - |

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

## References

* [MITRE](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2017-13721)
* [NVD](https://nvd.nist.gov/vuln/detail/CVE-2017-13721)
* [Launchpad](https://launchpad.net/bugs/cve/CVE-2017-13721)
* [Debian](https://security-tracker.debian.org/tracker/CVE-2017-13721)

### Related Ubuntu Security Notices (USN)

+ [USN-3453-1](https://usn.ubuntu.com/USN-3453-1)
+ X.Org X server vulnerabilities
+ 12 October 2017

### Other references

* <http://seclists.org/oss-sec/2017/q4/31>
* <https://www.cve.org/CVERecord?id=CVE-2017-13721>