Prototype pollution and path traversal in i18next-http-middleware via user-controlled language and namespace parameters_CVE-2026-41690

{
    "lastseen": "",
    "description": "18next-http-middleware is a middleware to be used with Node.js web frameworks like express or Fastify and also for Deno. Versions prior to 3.9.3 allow an unauthenticated HTTP client to pollute Object.prototype in the Node.js process hosting the middleware, via two unvalidated entry points that reach internal object-key writes: getResourcesHandler and missingKeyHandler. This can break authorisation checks (if (user.isAdmin) returning true for any user), cause type-confusion DoS, and depending on downstream code  it can be chained into RCE.",
    "published": "2026-05-08T15:24:12.014Z",
    "modified": "2026-05-08T15:24:12.014Z",
    "type": "cve",
    "title": "Prototype pollution and path traversal in i18next-http-middleware via user-controlled language and namespace parameters",
    "source": "GitHub_M",
    "references": "https://github.com/i18next/i18next-http-middleware/security/advisories/GHSA-5fgg-jcpf-8jjw",
    "id": "CVE-2026-41690",
    "bulletinFamily": "",
    "cwe": [
        "CWE-22",
        "CWE-1321"
    ],
    "cvelist": null,
    "sourceData": "i18next i18next-http-middleware < 3.9.3",
    "sourceHref": "",
    "cvss": {
        "score": 8.6,
        "severity": "HIGH",
        "vector": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:L",
        "version": "3.1"
    },
    "cvss2": [],
    "cvss3": {
        "version": "",
        "vectorString": "",
        "baseScore": 0,
        "baseSeverity": "",
        "attackVector": "",
        "attackComplexity": "",
        "privilegesRequired": "",
        "userInteraction": "",
        "scope": "",
        "confidentialityImpact": "",
        "integrityImpact": "",
        "availabilityImpact": "",
        "cvssV3": {
            "version": "",
            "vectorString": "",
            "baseScore": 0,
            "baseSeverity": "",
            "attackVector": "",
            "attackComplexity": "",
            "privilegesRequired": "",
            "userInteraction": "",
            "scope": "",
            "confidentialityImpact": "",
            "integrityImpact": "",
            "availabilityImpact": ""
        }
    },
    "href": "",
    "category_name": "CVE",
    "post_link": "",
    "product": "i18next-http-middleware",
    "version": "< 3.9.3",
    "vendor": "i18next",
    "ai_description": "Prototype pollution and path traversal vulnerability in i18next-http-middleware via user-controlled language and namespace parameters",
    "ai_severity": "High",
    "ai_vendor": "i18next",
    "ai_product": "i18next-http-middleware",
    "ai_version": "< 3.9.3",
    "ai_score": 8.6
}