@fastify/middie vulnerable to middleware authentication bypass in child plugin scopes_CVE-2026-6270

{
    "lastseen": "",
    "description": "@fastify/middie versions 9.3.1 and earlier do not register inherited middleware directly on child plugin engine instances. When a Fastify application registers authentication middleware in a parent scope and then registers child plugins with @fastify/middie, the child scope does not inherit the parent middleware. This allows unauthenticated requests to reach routes defined in child plugin scopes, bypassing authentication and authorization checks. Upgrade to @fastify/middie 9.3.2 to fix this issue. There are no workarounds.",
    "published": "2026-04-16T13:44:46.322Z",
    "modified": "2026-04-16T14:24:26.764Z",
    "type": "cve",
    "title": "@fastify/middie vulnerable to middleware authentication bypass in child plugin scopes",
    "source": "openjs",
    "references": "https://github.com/fastify/fastify-express/security/advisories/GHSA-hrwm-hgmj-7p9c\nhttps://github.com/fastify/middie/security/advisories/GHSA-72c6-fx6q-fr5w\nhttps://cna.openjsf.org/security-advisories.html",
    "id": "CVE-2026-6270",
    "bulletinFamily": "",
    "cwe": [
        "CWE-436"
    ],
    "cvelist": null,
    "sourceData": "@fastify/middie @fastify/middie 0",
    "sourceHref": "",
    "cvss": {
        "score": 9.1,
        "severity": "CRITICAL",
        "vector": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N",
        "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": "@fastify/middie",
    "version": "0",
    "vendor": "@fastify/middie",
    "ai_description": "Middleware authentication bypass vulnerability in @fastify/middie versions 9.3.1 and earlier, allowing unauthenticated requests to reach routes defined in child plugin scopes.",
    "ai_severity": "Critical",
    "ai_vendor": "Fastify",
    "ai_product": "@fastify/middie",
    "ai_version": "9.3.1 and earlier",
    "ai_score": 9.1
}