---
title: "CVE-2023-3138\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-2023-3138?format=md
keywords: index, follow
---

# CVE-2023-3138

Publication date 15 June 2023

Last updated 26 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-2023-3138?format=md#impact-score)

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## Description

A vulnerability was found in libX11. The security flaw occurs because the
functions in src/InitExt.c in libX11 do not check that the values provided
for the Request, Event, or Error IDs are within the bounds of the arrays
that those functions write to, using those IDs as array indexes. They trust
that they were called with values provided by an Xserver adhering to the
bounds specified in the X11 protocol, as all X servers provided by X.Org
do. As the protocol only specifies a single byte for these values, an
out-of-bounds value provided by a malicious server (or a malicious
proxy-in-the-middle) can only overwrite other portions of the Display
structure and not write outside the bounds of the Display structure itself,
possibly causing the client to crash with this memory corruption.

## Status

Show unmaintained releases

| Package | Ubuntu Release | Status |
| --- | --- | --- |
| libx11 | 23.04 lunar | Fixed 2:1.8.4-2ubuntu0.2 |
| 22.10 kinetic | Fixed 2:1.8.1-2ubuntu0.2 |
| 22.04 LTS jammy | Fixed 2:1.7.5-1ubuntu0.2 |
| 20.04 LTS focal | Fixed 2:1.6.9-2ubuntu1.5 |
| 18.04 LTS bionic | Fixed 2:1.6.4-3ubuntu0.4+esm1  Ubuntu Pro |
| 16.04 LTS xenial | Fixed 2:1.6.3-1ubuntu2.2+esm2  Ubuntu Pro |
| 14.04 LTS trusty | Fixed 2:1.6.2-1ubuntu2.1+esm3  Ubuntu Pro |

---

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

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## 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-2023-3138)
* [NVD](https://nvd.nist.gov/vuln/detail/CVE-2023-3138)
* [Launchpad](https://launchpad.net/bugs/cve/CVE-2023-3138)
* [Debian](https://security-tracker.debian.org/tracker/CVE-2023-3138)

### Related Ubuntu Security Notices (USN)

+ [USN-6168-1](https://usn.ubuntu.com/USN-6168-1)
+ libx11 vulnerability
+ 15 June 2023

+ [USN-6168-2](https://usn.ubuntu.com/USN-6168-2)
+ libx11 vulnerability
+ 20 June 2023

### Other references

* <https://www.cve.org/CVERecord?id=CVE-2023-3138>