Elysia vulnerable to prototype pollution with multiple standalone schema validation_CVE-2025-66456

{
    "lastseen": "",
    "description": "Elysia is a Typescript framework for request validation, type inference, OpenAPI documentation and client-server communication. Versions 1.4.0 through 1.4.16 contain a prototype pollution vulnerability in `mergeDeep` after merging results of two standard schema validations with the same key. Due to the ordering of merging, there must be an any type that is set as a standalone guard, to allow for the `__proto__ prop` to be merged. When combined with GHSA-8vch-m3f4-q8jf this allows for a full RCE by an attacker. This issue is fixed in version 1.4.17. To workaround, remove the `__proto__ key` from body.",
    "published": "2025-12-09T19:43:10.252Z",
    "modified": "2025-12-09T19:43:10.252Z",
    "type": "cve",
    "title": "Elysia vulnerable to prototype pollution with multiple standalone schema validation",
    "source": "GitHub_M",
    "references": "https://github.com/elysiajs/elysia/security/advisories/GHSA-hxj9-33pp-j2cc\nhttps://github.com/elysiajs/elysia/security/advisories/GHSA-8vch-m3f4-q8jf\nhttps://github.com/elysiajs/elysia/pull/1564\nhttps://github.com/elysiajs/elysia/commit/26935bf76ebc43b4a43d48b173fc853de43bb51e\nhttps://github.com/elysiajs/elysia/commit/3af978663e437dccc6c1a2a3aff4b74e1574849e",
    "id": "CVE-2025-66456",
    "bulletinFamily": "",
    "cwe": [
        "CWE-1321"
    ],
    "cvelist": null,
    "sourceData": "elysiajs elysia >= 1.4.0, < 1.4.17",
    "sourceHref": "",
    "cvss": {
        "score": 9.1,
        "severity": "CRITICAL",
        "vector": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N",
        "version": "4.0"
    },
    "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": "elysia",
    "version": ">= 1.4.0, < 1.4.17",
    "vendor": "elysiajs",
    "ai_description": "Prototype pollution vulnerability in `mergeDeep` allowing for full RCE by an attacker when combined with GHSA-8vch-m3f4-q8jf",
    "ai_severity": "Critical",
    "ai_vendor": "elysiajs",
    "ai_product": "elysia",
    "ai_version": "1.4.0-1.4.16",
    "ai_score": 9.1
}