---
title: "CVE-2019-18277\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-2019-18277?format=md
keywords: index, follow
---

# CVE-2019-18277

Publication date 23 October 2019

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-2019-18277?format=md#impact-score)

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## 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 |

---

* [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-2019-18277?format=md#patch-details)

### 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 |
| --- | --- |
| haproxy | * Upstream:   <https://git.haproxy.org/?p=haproxy-2.0.git;a=commit;h=196a7df44d8129d1adc795da020b722614d6a581> |

## 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 | High |
  | Availability impact | None |
* 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:H/A:N

## References

* [MITRE](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2019-18277)
* [NVD](https://nvd.nist.gov/vuln/detail/CVE-2019-18277)
* [Launchpad](https://launchpad.net/bugs/cve/CVE-2019-18277)
* [Debian](https://security-tracker.debian.org/tracker/CVE-2019-18277)

### Related Ubuntu Security Notices (USN)

+ [USN-4174-1](https://usn.ubuntu.com/USN-4174-1)
+ HAproxy vulnerability
+ 5 November 2019

### Other references

* <https://nathandavison.com/blog/haproxy-http-request-smuggling>
* <https://www.mail-archive.com/haproxy@formilux.org/msg34926.html>
* <https://www.cve.org/CVERecord?id=CVE-2019-18277>