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CVE-2020-28042

Estado: ModificadaMedia (5.3)—💥 PoC

ServiceStack versiones anteriores a 5.9.2, manejan inapropiadamente la verificación de la firma JWT a menos que una aplicación tenga una función ValidateToken personalizado que establezca una longitud mínima válida para una firma

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).

💥 Exploits públicos

Hay código de explotación o plantillas de detección públicos. No es lo mismo que explotación activa confirmada (KEV), pero aumenta el riesgo: parchee con prioridad.

⚠️ Las pruebas de concepto de GitHub no están verificadas: algunas son falsas o contienen malware. No las ejecute nunca fuera de un laboratorio aislado.

Tecnologías afectadas (1)

Servicestack — Servicestack

CWE

Referencias

JSON original (NVD)

Mostrar
{
  "id": "CVE-2020-28042",
  "cveTags": [],
  "metrics": {
    "cvssMetricV2": [
      {
        "type": "Primary",
        "source": "nvd@nist.gov",
        "cvssData": {
          "version": "2.0",
          "baseScore": 5,
          "accessVector": "NETWORK",
          "vectorString": "AV:N/AC:L/Au:N/C:N/I:P/A:N",
          "authentication": "NONE",
          "integrityImpact": "PARTIAL",
          "accessComplexity": "LOW",
          "availabilityImpact": "NONE",
          "confidentialityImpact": "NONE"
        },
        "acInsufInfo": false,
        "impactScore": 2.9,
        "baseSeverity": "MEDIUM",
        "obtainAllPrivilege": false,
        "exploitabilityScore": 10,
        "obtainUserPrivilege": false,
        "obtainOtherPrivilege": false,
        "userInteractionRequired": false
      }
    ],
    "cvssMetricV31": [
      {
        "type": "Primary",
        "source": "nvd@nist.gov",
        "cvssData": {
          "scope": "UNCHANGED",
          "version": "3.1",
          "baseScore": 5.3,
          "attackVector": "NETWORK",
          "baseSeverity": "MEDIUM",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N",
          "integrityImpact": "LOW",
          "userInteraction": "NONE",
          "attackComplexity": "LOW",
          "availabilityImpact": "NONE",
          "privilegesRequired": "NONE",
          "confidentialityImpact": "NONE"
        },
        "impactScore": 1.4,
        "exploitabilityScore": 3.9
      }
    ]
  },
  "affected": [
    {
      "source": "cve@mitre.org",
      "affectedData": [
        {
          "vendor": "n/a",
          "product": "n/a",
          "versions": [
            {
              "status": "affected",
              "version": "n/a"
            }
          ]
        }
      ]
    }
  ],
  "published": "2020-11-02T21:15:31.320",
  "references": [
    {
      "url": "https://forums.servicestack.net/t/servicestack-v5-9-2-released/8850",
      "tags": [
        "Release Notes",
        "Vendor Advisory"
      ],
      "source": "cve@mitre.org"
    },
    {
      "url": "https://github.com/ServiceStack/ServiceStack/commit/540d4060e877a03ae95343c1a8560a26768585ee",
      "tags": [
        "Patch",
        "Third Party Advisory"
      ],
      "source": "cve@mitre.org"
    },
    {
      "url": "https://www.shielder.it/advisories/servicestack-jwt-signature-verification-bypass/",
      "tags": [
        "Exploit",
        "Third Party Advisory"
      ],
      "source": "cve@mitre.org"
    },
    {
      "url": "https://www.shielder.it/blog/2020/11/re-discovering-a-jwt-authentication-bypass-in-servicestack/",
      "tags": [
        "Exploit",
        "Third Party Advisory"
      ],
      "source": "cve@mitre.org"
    },
    {
      "url": "https://forums.servicestack.net/t/servicestack-v5-9-2-released/8850",
      "tags": [
        "Release Notes",
        "Vendor Advisory"
      ],
      "source": "af854a3a-2127-422b-91ae-364da2661108"
    },
    {
      "url": "https://github.com/ServiceStack/ServiceStack/commit/540d4060e877a03ae95343c1a8560a26768585ee",
      "tags": [
        "Patch",
        "Third Party Advisory"
      ],
      "source": "af854a3a-2127-422b-91ae-364da2661108"
    },
    {
      "url": "https://www.shielder.it/advisories/servicestack-jwt-signature-verification-bypass/",
      "tags": [
        "Exploit",
        "Third Party Advisory"
      ],
      "source": "af854a3a-2127-422b-91ae-364da2661108"
    },
    {
      "url": "https://www.shielder.it/blog/2020/11/re-discovering-a-jwt-authentication-bypass-in-servicestack/",
      "tags": [
        "Exploit",
        "Third Party Advisory"
      ],
      "source": "af854a3a-2127-422b-91ae-364da2661108"
    }
  ],
  "vulnStatus": "Modified",
  "weaknesses": [
    {
      "type": "Primary",
      "source": "nvd@nist.gov",
      "description": [
        {
          "lang": "en",
          "value": "CWE-347"
        }
      ]
    }
  ],
  "descriptions": [
    {
      "lang": "en",
      "value": "ServiceStack before 5.9.2 mishandles JWT signature verification unless an application has a custom ValidateToken function that establishes a valid minimum length for a signature."
    },
    {
      "lang": "es",
      "value": "ServiceStack versiones anteriores a 5.9.2, manejan inapropiadamente la verificación de la firma JWT a menos que una aplicación tenga una función ValidateToken personalizado que establezca una longitud mínima válida para una firma"
    }
  ],
  "lastModified": "2026-06-17T03:10:03.410",
  "configurations": [
    {
      "nodes": [
        {
          "negate": false,
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:a:servicestack:servicestack:*:*:*:*:*:*:*:*",
              "vulnerable": true,
              "matchCriteriaId": "3CEA8F43-A1EA-4A89-9533-01F5F8163C56",
              "versionEndExcluding": "5.9.2"
            }
          ],
          "operator": "OR"
        }
      ]
    }
  ],
  "sourceIdentifier": "cve@mitre.org"
}