# CVE-2019-18277: Other in n/a

> Attackers can exploit HTTP request smuggling in HAProxy legacy mode with specific reuse settings to bypass security controls.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 23 Oct 2019
- **Updated:** 5 Aug 2024
- **Also known as:** CLSA-2026-1776336742, CLSA-2026-1776337242, DEBIAN-CVE-2019-18277, GHSA-7r84-r685-grmg, SUSE-SU-2019:3125-1, SUSE-SU-2019:3126-1, SUSE-SU-2019:3288-1, UBUNTU-CVE-2019-18277, USN-4174-1, openSUSE-SU-2019:2626-1, openSUSE-SU-2019:2645-1

## What is CVE-2019-18277?

CVE-2019-18277 is a high-severity vulnerability in n/a, published on 23 Oct 2019. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official 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).

Weakness: CWE-444 (Inconsistent Interpretation of HTTP Requests)

## Which versions are affected by CVE-2019-18277?

It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `haproxy` | SUSE:HPE Helion OpenStack 8 | All versions | 1.6.11-11.3.1 |
| `haproxy` | SUSE:Linux Enterprise High Availability Extension 12 SP3 | All versions | 1.6.11-11.3.1 |
| `haproxy` | SUSE:Linux Enterprise High Availability Extension 12 SP4 | All versions | 1.6.11-11.3.1 |
| `haproxy` | SUSE:Linux Enterprise High Availability Extension 12 SP5 | All versions | 1.6.11-11.3.1 |
| `haproxy` | SUSE:Linux Enterprise High Availability Extension 15 | All versions | 2.0.10+git0.ac198b92-3.15.1 |
| `haproxy` | SUSE:Linux Enterprise High Availability Extension 15 SP1 | All versions | 2.0.10+git0.ac198b92-8.8.1 |
| `haproxy` | SUSE:OpenStack Cloud 7 | All versions | 1.6.11-11.3.1 |
| `haproxy` | SUSE:OpenStack Cloud 8 | All versions | 1.6.11-11.3.1 |
| `haproxy` | SUSE:OpenStack Cloud 9 | All versions | 1.6.11-11.3.1 |
| `haproxy` | SUSE:OpenStack Cloud Crowbar 8 | All versions | 1.6.11-11.3.1 |
| `haproxy` | SUSE:OpenStack Cloud Crowbar 9 | All versions | 1.6.11-11.3.1 |
| `haproxy` | openSUSE:Leap 15.0 | All versions | 2.0.10+git0.ac198b92-lp150.2.16.1 |
| `haproxy` | openSUSE:Leap 15.1 | All versions | 2.0.10+git0.ac198b92-lp151.2.6.1 |

Products: Haproxy Haproxy.

## How do I fix CVE-2019-18277?

Upgrade to a fixed version.

## Is CVE-2019-18277 being exploited?

There is no known exploitation of CVE-2019-18277 in the wild and no public exploit code.

## Other vulnerabilities in n/a

- [CVE-2026-55203](https://insights.sbomify.com/CVE-2026-55203/): HAProxy - Integer Overflow in FCGI Demux Record Length Field (critical 9.0)
- [CVE-2026-55204](https://insights.sbomify.com/CVE-2026-55204/): HAProxy - NULL Pointer Dereference in hpack_dht_insert Function (high 8.7)
- [CVE-2023-45539](https://insights.sbomify.com/CVE-2023-45539/): Information disclosure in n/a (high 8.2)
- [CVE-2024-45506](https://insights.sbomify.com/CVE-2024-45506/): Denial of service in n/a (high 7.5)
- [CVE-2023-0836](https://insights.sbomify.com/CVE-2023-0836/): Information disclosure in HAProxy (high 7.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2019-18277 and fix it if it is affected.

What it is: CVE-2019-18277 is a high-severity vulnerability in n/a, published on 23 Oct 2019. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2019-18277 in the wild and no public exploit code.

Affected product: n/a. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2019-18277/ (Markdown: https://insights.sbomify.com/CVE-2019-18277/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2019-18277
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2019-18277
- OSV: https://osv.dev/vulnerability/CVE-2019-18277

---
From sbomify Insights: https://insights.sbomify.com/CVE-2019-18277/
Summaries are generated and may contain mistakes; the official description above is the record.