CVE-2023-23936Public exploitNetwork attack vector

HTTP header injection via unchecked Host value

Published Feb 16, 2023 · Updated Mar 10, 2025

CRLF injection in Undici 2.0.0 through versions before 5.19.1 allows context-dependent attackers to inject headers through the Host value. The processHeader function assigns the special-cased Host value to request.host without applying the header-character validation used for other headers. Exploitation requires an application to place attacker-controlled CR or LF characters in headers.host and send the resulting request.

CVSS severity4.6
Medium
EPSS probability1.13%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

CRLF injection in Undici 2.0.0 through versions before 5.19.1 allows context-dependent attackers to inject headers through the Host value. The processHeader function assigns the special-cased Host value to request.host without applying the header-character validation used for other headers. Exploitation requires an application to place attacker-controlled CR or LF characters in headers.host and send the resulting request.

The record

CVE
CVE-2023-23936
Published
Feb 16, 2023
Updated
Mar 10, 2025
Vendor
Node.js
Product
Undici
Classifications
CWE-74, CWE-93
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Feb 16, 2023CVE publishedPublication date reported by the CVE source.
  2. Mar 10, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=>=2.0.0, < 5.19.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Node.js · Undiciversion=>=2.0.0, < 5.19.1

Published CVSS scores

5.4NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N
4.6GitHubCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:L/I:L/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-74Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection')
CWE-93Improper Neutralization of CRLF Sequences ('CRLF Injection')

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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