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CVE-2025-66456

Estado: AnalizadaCrítica (9.1)—

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.

CVSS

Probabilidad de explotación (EPSS)

EPSS (Exploit Prediction Scoring System, de FIRST) estima la probabilidad de que una vulnerabilidad sea explotada en 30 días. Complementa a CVSS (impacto) y a CISA KEV (explotación confirmada).

🎯 Técnicas ATT&CK

Cómo se explota esta vulnerabilidad y qué consigue el atacante, en el lenguaje de MITRE ATT&CK.

Vulnerabilidad de contaminación de prototipos en framework web Elysia accesible remotamente sin autenticación (PR:N) que permite RCE mediante manipulación de esquema. AV:N y PR:N indican T1190; impacto en ejecución de código confirmado por 'full RCE' en descripción.

Inferido por nuestro agente de análisis a partir de la descripción oficial, el vector CVSS y la CWE, y comprobado por un supervisor. Puede contener errores.

🛡️ Mitigaciones ATT&CK que cubren estas técnicas

Privileged Account ManagementVulnerability ScanningRestrict Web-Based ContentNetwork SegmentationLimit Software InstallationLimit Access to Resource Over Network

Tecnologías afectadas (1)

Elysiajs — Elysia

CWE

Referencias

JSON original (NVD)

Mostrar
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  "id": "CVE-2025-66456",
  "cveTags": [],
  "metrics": {
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        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
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          "id": "CVE-2025-66456",
          "role": "CISA Coordinator",
          "options": [
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              "exploitation": "poc"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "total"
            }
          ],
          "version": "2.0.3",
          "timestamp": "2025-12-09T20:11:35.267669Z"
        }
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          "integrityImpact": "HIGH",
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          "Safety": "NOT_DEFINED",
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          "Recovery": "NOT_DEFINED",
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          "attackVector": "NETWORK",
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          "exploitMaturity": "NOT_DEFINED",
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          "integrityRequirement": "NOT_DEFINED",
          "modifiedAttackVector": "NOT_DEFINED",
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          "vulnAvailabilityImpact": "NONE",
          "availabilityRequirement": "NOT_DEFINED",
          "modifiedUserInteraction": "NOT_DEFINED",
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          "subConfidentialityImpact": "NONE",
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          "confidentialityRequirement": "NOT_DEFINED",
          "modifiedAttackRequirements": "NOT_DEFINED",
          "modifiedPrivilegesRequired": "NOT_DEFINED",
          "modifiedSubIntegrityImpact": "NOT_DEFINED",
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          "vulnerabilityResponseEffort": "NOT_DEFINED",
          "modifiedSubAvailabilityImpact": "NOT_DEFINED",
          "modifiedVulnAvailabilityImpact": "NOT_DEFINED",
          "modifiedSubConfidentialityImpact": "NOT_DEFINED",
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      "affectedData": [
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            }
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  "references": [
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      "url": "https://github.com/elysiajs/elysia/commit/26935bf76ebc43b4a43d48b173fc853de43bb51e",
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      "url": "https://github.com/elysiajs/elysia/pull/1564",
      "tags": [
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    {
      "url": "https://github.com/elysiajs/elysia/security/advisories/GHSA-8vch-m3f4-q8jf",
      "tags": [
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    },
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      "url": "https://github.com/elysiajs/elysia/security/advisories/GHSA-8vch-m3f4-q8jf",
      "tags": [
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      "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0"
    },
    {
      "url": "https://github.com/elysiajs/elysia/security/advisories/GHSA-hxj9-33pp-j2cc",
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        "Patch",
        "Vendor Advisory"
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      "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0"
    }
  ],
  "vulnStatus": "Analyzed",
  "weaknesses": [
    {
      "type": "Secondary",
      "source": "security-advisories@github.com",
      "description": [
        {
          "lang": "en",
          "value": "CWE-1321"
        }
      ]
    }
  ],
  "descriptions": [
    {
      "lang": "en",
      "value": "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."
    }
  ],
  "lastModified": "2026-06-17T09:56:52.520",
  "configurations": [
    {
      "nodes": [
        {
          "negate": false,
          "cpeMatch": [
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              "criteria": "cpe:2.3:a:elysiajs:elysia:*:*:*:*:*:node.js:*:*",
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              "versionEndExcluding": "1.4.17",
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            }
          ],
          "operator": "OR"
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  "sourceIdentifier": "security-advisories@github.com"
}