CVE-2019-18277

Publication date 23 October 2019

Last updated 25 August 2025

Ubuntu priority

Cvss 3 Severity Score

Description

A flaw was found in HAProxy before 2.0.6. In legacy mode, messages featuring a transfer-encoding header missing the "chunked" value were not being correctly rejected. The impact was limited but if combined with the "http-reuse always" setting, it could be used to help construct an HTTP request smuggling attack against a vulnerable component employing a lenient parser that would ignore the content-length header as soon as it saw a transfer-encoding one (even if not entirely valid according to the specification).

Status

Show unmaintained releases

Package	Ubuntu Release	Status
haproxy	19.10 eoan	Fixed 2.0.5-1ubuntu0.2
	19.04 disco	Fixed 1.8.19-1ubuntu1.2
	18.04 LTS bionic	Fixed 1.8.8-1ubuntu0.7
	16.04 LTS xenial	Fixed 1.6.3-1ubuntu0.3
	14.04 LTS trusty	Not in release

Patch details

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

Package	Patch details
haproxy	Upstream: https://git.haproxy.org/?p=haproxy-2.0.git;a=commit;h=196a7df44d8129d1adc795da020b722614d6a581

Severity score breakdown

Parameter	Value
Base score	7.5 · High
Attack vector	Network
Attack complexity	Low
Privileges required	None
User interaction	None
Scope	Unchanged
Confidentiality	None
Integrity impact	High
Availability impact	None
Vector	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

References

Related Ubuntu Security Notices (USN)

USN-4174-1
HAproxy vulnerability
5 November 2019