CRLF Injection in Nodejs ‘undici’ via host

Answer in brief

CVE-2023-23936 records a Medium severity (CVSS 4.6) vulnerability in CRLF Injection in Nodejs ‘undici’ via host. The current sources do not mark it as known exploited. The current feed maps undici (npm). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Feb 16, 2023Updated Sep 10, 2026Source checked Sep 10, 2026First seen by HOL Sep 10, 2026Material review Sep 10, 2026

Upstream Advisory

Key facts

Risk: Medium · CVSS 4.6
Exploitation: Not marked as known exploited
Affected software: 1 mapped package or product
Fix availability: Available

Why this deserves its current priority

CVSS is 4.6. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps undici (npm). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
undicinpm	>=2.0.0 <5.19.1	5.19.1

Recommended response

Check inventory. Check lockfiles and deployed manifests for undici.
Review the reported fix. Update undici to 5.19.1 if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

Published upstream
Feb 16, 2023
Evidence: source:osv:source_dates:source-dates:record
Source modified
Sep 10, 2026
Evidence: source:osv:source_dates:source-dates:record
First seen by HOL
Sep 10, 2026

Sources and claim methodology

Upstream source description

### Impact undici library does not protect `host` HTTP header from CRLF injection vulnerabilities. ### Patches This issue was patched in Undici v5.19.1. ### Workarounds Sanitize the `headers.host` string before passing to undici. ### References Reported at https://hackerone.com/reports/1820955. ### Credits Thank you to Zhipeng Zhang ([@timon8](https://hackerone.com/timon8)) for reporting this vulnerability.

Quoted source text, attributed separately from HOL analysis.