---
title: "CVE-2016-8740\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-2016-8740?format=md
keywords: index, follow
---

# CVE-2016-8740

Publication date 5 December 2016

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-2016-8740?format=md#impact-score)

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## Description

The mod\_http2 module in the Apache HTTP Server 2.4.17 through 2.4.23, when
the Protocols configuration includes h2 or h2c, does not restrict
request-header length, which allows remote attackers to cause a denial of
service (memory consumption) via crafted CONTINUATION frames in an HTTP/2
request.

[Read the notes from the security team](https://ubuntu.com/security/CVE-2016-8740?format=md#notes)

## Status

Show unmaintained releases

| Package | Ubuntu Release | Status |
| --- | --- | --- |
| apache2 | 17.04 zesty | Not affected |
| 16.10 yakkety | Not affected |
| 16.04 LTS xenial | Not affected |
| 14.04 LTS trusty | Not affected |
| 12.04 LTS precise | 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-2016-8740?format=md#patch-details)

## Notes

---

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

mod\_http2 is not built in Ubuntu because it is considered
experimental.

### 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:   [29c63b7](https://github.com/apache/httpd/commit/29c63b786ae028d82405421585e91283c8fa0da3) * Upstream:   <https://svn.apache.org/viewvc?view=revision&revision=1772579> |

## 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:3.0/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-2016-8740)
* [NVD](https://nvd.nist.gov/vuln/detail/CVE-2016-8740)
* [Launchpad](https://launchpad.net/bugs/cve/CVE-2016-8740)
* [Debian](https://security-tracker.debian.org/tracker/CVE-2016-8740)

### Other references

* <http://www.openwall.com/lists/oss-security/2016/12/05/14>
* <https://www.cve.org/CVERecord?id=CVE-2016-8740>