CVE-2016-1546

Publication date 6 July 2016

Last updated 25 August 2025

Ubuntu priority

Cvss 3 Severity Score

Description

The Apache HTTP Server 2.4.17 and 2.4.18, when mod_http2 is enabled, does not limit the number of simultaneous stream workers for a single HTTP/2 connection, which allows remote attackers to cause a denial of service (stream-processing outage) via modified flow-control windows.

Read the notes from the security team

Status

Show unmaintained releases

Package	Ubuntu Release	Status
apache2	16.04 LTS xenial	Not affected
	15.10 wily	Not affected
	14.04 LTS trusty	Not affected
	12.04 LTS precise	Not affected

Notes

sbeattie

http/2 support disabled for xenial, added upsteam in 2.17 fixed upstream in 2.4.20

Patch details

For informational purposes only. We recommend not to cherry-pick updates. How can I get the fixes?

Package	Patch details
apache2	Upstream: http://svn.apache.org/viewvc?view=revision&revision=1734413

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