CVE-2023-23936 — Undici is an HTTP/1

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` str

01What is this vulnerability?

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.

02Affected products

Vendor	Product	Versions
nodejs	undici	>=2.0.0, < 5.19.1

03Active exploitation status

Not currently listed on the CISA Known Exploited Vulnerabilities (KEV) catalog. EPSS is the best forward-looking signal — see the EPSS row above.

04Recommended remediation

• Patch to a fixed version listed in the vendor advisory (see references below).
• Mitigate with WAF rules, network egress filters, or feature flags where the patch is not yet available.
• Hunt historical logs for exploitation indicators — see Detection signatures below.

05Technical details

For the full vendor write-up, exploit chains, and reference implementations, see the references list in section 09.

06Detection signatures

Ask SARA in chat to draft a starting detection for this CVE in your stack of choice.

07Related CVEs

No directly-cited follow-up CVEs in the KB record for this advisory. The references list in section 09 carries the vendor cross-references.

08Timeline

• Published: 2023-02-16T17:30:23.968Z
• Last modified: 2025-03-10T21:10:26.495Z

09References

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