# Improper header name validation in guzzlehttp/psr7

Advisory record · `GHSA-wxmh-65f7-jcvw`

- **Identifiers:** `GHSA-wxmh-65f7-jcvw` · `CVE-2023-29197` · `PKSA-hn62-zkx4-1y5q`
- **State:** Confirmed
- **Severity:** CVSS 5.3 Medium
- **Critical:** No
- **Weakness (CWE):** [CWE-436](https://cwe.mitre.org/data/definitions/436.html)
- **Tags:** [CWE-436](https://agentprime.io/advisories/tag/cwe-436.md)
- **Published:** 19 Apr 2023
- **Updated:** 4 Feb 2026
- **Reviewed by a person:** No

Published by the GitHub Advisory Database at 19 Apr 2023, 18:25 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

## Affected packages

- `guzzlehttp/psr7` (Packagist): affected `<1.9.1 || >=2.0.0, <2.4.5`; fixed in `1.9.1`, `2.4.5`

## Machine-written summary

Summary written by Claude Haiku from the source advisory. Not reviewed by a person.

> Versions of guzzlehttp/psr7 before 1.9.1, and from 2.0.0 before 2.4.5, do not properly validate newline characters in HTTP header names and values. An attacker who can supply header input could insert a newline that some servers accept as the end of the header list, which may allow header injection. Upgrade to 1.9.1 or 2.4.5. No workarounds are listed.

Written 3 Nov 2026.

## 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

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

- **CISA KEV:** Not listed.
- **EPSS:** 0.012, the 68th percentile, on 7 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

## Timeline

- 31 Oct 2026, 14:26 UTC: First seen by agentprime
- 31 Oct 2026, 14:26 UTC: [Confirmed by OSV](https://osv.dev/vulnerability/GHSA-wxmh-65f7-jcvw)

## Sources

- [GitHub Advisory Database: GHSA-wxmh-65f7-jcvw](https://github.com/advisories/GHSA-wxmh-65f7-jcvw)
- [OSV: GHSA-wxmh-65f7-jcvw](https://osv.dev/vulnerability/GHSA-wxmh-65f7-jcvw)
- <https://github.com/guzzle/psr7/security/advisories/GHSA-q7rv-6hp3-vh96>
- <https://github.com/guzzle/psr7/security/advisories/GHSA-wxmh-65f7-jcvw>
- <https://nvd.nist.gov/vuln/detail/CVE-2023-29197>
- <https://cve.mitre.org/cgi-bin/cvename.cgi?name=2022-24775>
- <https://github.com/FriendsOfPHP/security-advisories/blob/master/guzzlehttp/psr7/CVE-2023-29197.yaml>
- <https://github.com/guzzle/psr7>
- <https://lists.debian.org/debian-lts-announce/2023/12/msg00028.html>
- <https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/FJANWDXJZE5BGLN4MQ4FEHV5LJ6CMKQF>
- <https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/O35UN4IK6VS2LXSRWUDFWY7NI73RKY2U>
- <https://www.rfc-editor.org/rfc/rfc7230#section-3.2.4>

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-wxmh-65f7-jcvw>, 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-wxmh-65f7-jcvw/>. Everything for agents: <https://agentprime.io/llms.txt>.