# HTTP Smuggling via Transfer-Encoding Header in Puma

Advisory record · `GHSA-w64w-qqph-5gxm`

- **Identifiers:** `GHSA-w64w-qqph-5gxm` · `CVE-2020-11077`
- **State:** Confirmed
- **Severity:** CVSS 6.8 Medium
- **Critical:** No
- **Weakness (CWE):** [CWE-444](https://cwe.mitre.org/data/definitions/444.html)
- **Tags:** [HTTP request smuggling](https://agentprime.io/advisories/tag/request-smuggling.md)
- **Published:** 22 May 2020
- **Updated:** 10 Sept 2026
- **Reviewed by a person:** No

Published by the GitHub Advisory Database at 22 May 2020, 14:55 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

## Affected packages

- `puma` (RubyGems): affected `<3.12.6 || >=4.0.0, <4.3.5`; fixed in `3.12.6`, `4.3.5`

## Not analysed yet

We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.

## Severity and exploitation

- 6.8 Medium, CVSS 3.1: `CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:H/A:N`, from CNA (GitHub_M)

- **CISA KEV:** Not listed.
- **EPSS:** 0.029, the 86th percentile, on 7 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

## Timeline

- 31 Oct 2026, 15:16 UTC: First seen by agentprime
- 31 Oct 2026, 15:16 UTC: [Confirmed by OSV](https://osv.dev/vulnerability/GHSA-w64w-qqph-5gxm)

## Sources

- [GitHub Advisory Database: GHSA-w64w-qqph-5gxm](https://github.com/advisories/GHSA-w64w-qqph-5gxm)
- [OSV: GHSA-w64w-qqph-5gxm](https://osv.dev/vulnerability/GHSA-w64w-qqph-5gxm)
- <https://github.com/puma/puma/security/advisories/GHSA-w64w-qqph-5gxm>
- <https://nvd.nist.gov/vuln/detail/CVE-2020-11077>
- <https://github.com/puma/puma>
- <https://github.com/puma/puma/blob/master/History.md#434435-and-31253126--2020-05-22>
- <https://github.com/rubysec/ruby-advisory-db/blob/master/gems/puma/CVE-2020-11077.yml>
- <https://lists.debian.org/debian-lts-announce/2020/10/msg00009.html>
- <https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/SKIY5H67GJIGJL6SMFWFLUQQQR3EMVPR>
- <http://lists.opensuse.org/opensuse-security-announce/2020-07/msg00034.html>
- <http://lists.opensuse.org/opensuse-security-announce/2020-07/msg00038.html>

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.

## Check whether this affects you

A Match means an installed version is in the affected range above. Most don’t affect the app; agentprime hasn’t analysed this one yet.

- With the agentprime MCP server (<https://api.agentprime.io/mcp>), ask your agent to check the project: `check_lockfile` sends a lockfile, `check_packages` a list of installed packages, and both return the Matches and the upgrades that clear them. `get_advisory` returns this record. Setup: <https://agentprime.io/mcp.md>
- In a browser: <https://agentprime.io/check/> reads your lockfile in the browser, never uploading it.
- Whether it touches your code, with file and line: the Claude Code plugin, <https://agentprime.io/plugin.md>
- As JSON: <https://api.agentprime.io/v1/advisories/GHSA-w64w-qqph-5gxm>, or `POST https://api.agentprime.io/v1/match` with your packages (<https://agentprime.io/api.md>)

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The web page: <https://agentprime.io/advisories/GHSA-w64w-qqph-5gxm/>. Everything for agents: <https://agentprime.io/llms.txt>.