---
title: "CVE-2018-11763\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-2018-11763?format=md
keywords: index, follow
---

# CVE-2018-11763

Publication date 25 September 2018

Last updated 25 August 2025

---

Ubuntu priority

**Medium**

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

## Cvss 3 Severity Score

**5.9 · Medium**

[Score breakdown](https://ubuntu.com/security/CVE-2018-11763?format=md#impact-score)

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## Description

In Apache HTTP Server 2.4.17 to 2.4.34, by sending continuous, large
SETTINGS frames a client can occupy a connection, server thread and CPU
time without any connection timeout coming to effect. This affects only
HTTP/2 connections. A possible mitigation is to not enable the h2 protocol.

[Read the notes from the security team](https://ubuntu.com/security/CVE-2018-11763?format=md#notes)

## Status

Show unmaintained releases

| Package | Ubuntu Release | Status |
| --- | --- | --- |
| apache2 | 18.04 LTS bionic | Fixed 2.4.29-1ubuntu4.4 |
| 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)
* [Patch details](https://ubuntu.com/security/CVE-2018-11763?format=md#patch-details)

## Notes

---

### [mdeslaur](https://launchpad.net/~mdeslaur)

artful and older don't enable http2 in the build.
see CVE-2018-1302 for a whole http2 backport requirement

### 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 |
| --- | --- |
| apache2 | * Upstream:   <https://svn.apache.org/viewvc?view=revision&revision=1840757> * Upstream:   [484aba5](https://github.com/apache/httpd/commit/484aba5048e3457dc1d15189f1910d007b1a4a76) |

## Severity score breakdown

CVSS version:
CVSS v3.0

**Base score**

5.9 · Medium

* Base metrics

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

  | Parameter | Value |
  | --- | --- |
  | Base score | 5.9 · Medium |
  | Exploitability score | - |
  | Impact score | - |

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

## References

* [MITRE](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2018-11763)
* [NVD](https://nvd.nist.gov/vuln/detail/CVE-2018-11763)
* [Launchpad](https://launchpad.net/bugs/cve/CVE-2018-11763)
* [Debian](https://security-tracker.debian.org/tracker/CVE-2018-11763)

### Related Ubuntu Security Notices (USN)

+ [USN-3783-1](https://usn.ubuntu.com/USN-3783-1)
+ Apache HTTP Server vulnerabilities
+ 3 October 2018

### Other references

* <http://www.securitytracker.com/id/1041713>
* <https://httpd.apache.org/security/vulnerabilities_24.html>
* <https://www.cve.org/CVERecord?id=CVE-2018-11763>