CVE-2026-41683Network attack vector

Response splitting and service interruption via header injection

Published May 8, 2026 · Updated May 8, 2026

HTTP response splitting in i18next-http-middleware before 3.9.3 allows remote attackers to inject headers via a crafted language value. The middleware passes the detected value through an HTML encoder that preserves control characters, then supplies it to res.setHeader as Content-Language. Exposure requires a raw detected value; older Node.js accepts the injected header, while newer Node.js throws an uncaught error that interrupts service.

CVSS severity8.6
High
EPSS probability0.33%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

HTTP response splitting in i18next-http-middleware before 3.9.3 allows remote attackers to inject headers via a crafted language value. The middleware passes the detected value through an HTML encoder that preserves control characters, then supplies it to res.setHeader as Content-Language. Exposure requires a raw detected value; older Node.js accepts the injected header, while newer Node.js throws an uncaught error that interrupts service.

The record

CVE
CVE-2026-41683
Published
May 8, 2026
Updated
May 8, 2026
Vendor
i18next
Product
i18next-http-middleware
Classifications
CWE-113, CWE-79, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 8, 2026CVE publishedPublication date reported by the CVE source.
  2. May 8, 2026Record 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=< 3.9.3

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

i18next · i18next-http-middlewareversion=< 3.9.3

Published CVSS scores

8.6GitHubCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:L

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.

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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
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-113Improper Neutralization of CRLF Sequences in HTTP Headers ('HTTP Request/Response Splitting')
CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1190Exploit Public-Facing Application

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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