CVE-2026-41690Public exploitNetwork attack vector

Unauthenticated prototype pollution via unsafe identifier writes

Published May 8, 2026 · Updated May 8, 2026

Prototype pollution in i18next-http-middleware before 3.9.3 allows remote attackers to modify Object.prototype via HTTP requests. getResourcesHandler passes unvalidated language and namespace keys to setPath, while missingKeyHandler iterates inherited request-body properties with for...in. Exposed handlers permit process-wide property injection and denial of service; configured filesystem or HTTP backends also permit path traversal or SSRF.

CVSS severity8.6
High
EPSS probability0.31%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Prototype pollution in i18next-http-middleware before 3.9.3 allows remote attackers to modify Object.prototype via HTTP requests. getResourcesHandler passes unvalidated language and namespace keys to setPath, while missingKeyHandler iterates inherited request-body properties with for...in. Exposed handlers permit process-wide property injection and denial of service; configured filesystem or HTTP backends also permit path traversal or SSRF.

The record

CVE
CVE-2026-41690
Published
May 8, 2026
Updated
May 8, 2026
Vendor
i18next
Product
i18next-http-middleware
Classifications
CWE-22, CWE-1321, 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

8.6GitHub, Inc.CVSS: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.

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

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-22Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
CWE-1321Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution')
T1190Exploit Public-Facing Application

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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