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CVE-2026-33996

Estado: AnalizadaMedia (5.8)—

LibJWT is a C JSON Web Token Library. Starting in version 3.0.0 and prior to version 3.3.0, the JWK parsing for RSA-PSS did not protect against a NULL value when expecting to parse JSON string values. A specially crafted JWK file could exploit this behavior by using integers in places where the code expected a string. This was fixed in v3.3.0. A workaround is available. Users importing keys through a JWK file should not do so from untrusted sources. Use the `jwk2key` tool to check for validity of a JWK file. Likewise, if possible, do not use JWK files with RSA-PSS keys.

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).

Tecnologías afectadas (1)

Libjwt — Libjwt

CWE

Referencias

JSON original (NVD)

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  "id": "CVE-2026-33996",
  "cveTags": [],
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          "id": "CVE-2026-33996",
          "role": "CISA Coordinator",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "no"
            },
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              "technicalImpact": "partial"
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          "version": "2.0.3",
          "timestamp": "2026-03-31T18:50:38.575748Z"
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          "vectorString": "CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H",
          "integrityImpact": "NONE",
          "userInteraction": "REQUIRED",
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          "availabilityImpact": "HIGH",
          "privilegesRequired": "NONE",
          "confidentialityImpact": "NONE"
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        "type": "Secondary",
        "source": "security-advisories@github.com",
        "cvssData": {
          "Safety": "NOT_DEFINED",
          "version": "4.0",
          "Recovery": "NOT_DEFINED",
          "baseScore": 5.8,
          "Automatable": "NOT_DEFINED",
          "attackVector": "ADJACENT",
          "baseSeverity": "MEDIUM",
          "valueDensity": "NOT_DEFINED",
          "vectorString": "CVSS:4.0/AV:A/AC:H/AT:P/PR:N/UI:A/VC:L/VI:L/VA:H/SC:L/SI:L/SA:L/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X",
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          "modifiedAttackRequirements": "NOT_DEFINED",
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          "modifiedSubAvailabilityImpact": "NOT_DEFINED",
          "modifiedVulnAvailabilityImpact": "NOT_DEFINED",
          "modifiedSubConfidentialityImpact": "NOT_DEFINED",
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  "published": "2026-03-27T23:17:14.590",
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      "url": "https://github.com/benmcollins/libjwt/commit/cfd890286fa49ae61b534c937c9f0428b5c6034c",
      "tags": [
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  "vulnStatus": "Analyzed",
  "weaknesses": [
    {
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      "source": "security-advisories@github.com",
      "description": [
        {
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          "value": "CWE-476"
        }
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  ],
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      "lang": "en",
      "value": "LibJWT is a C JSON Web Token Library. Starting in version 3.0.0 and prior to version 3.3.0, the JWK parsing for RSA-PSS did not protect against a NULL value when expecting to parse JSON string values. A specially crafted JWK file could exploit this behavior by using integers in places where the code expected a string. This was fixed in v3.3.0. A workaround is available. Users importing keys through a JWK file should not do so from untrusted sources. Use the `jwk2key` tool to check for validity of a JWK file. Likewise, if possible, do not use JWK files with RSA-PSS keys."
    },
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      "lang": "es",
      "value": "LibJWT es una biblioteca C de JSON Web Token. A partir de la versión 3.0.0 y antes de la versión 3.3.0, el análisis JWK para RSA-PSS no protegía contra un valor NULL cuando esperaba analizar valores de cadena JSON. Un archivo JWK especialmente diseñado podría explotar este comportamiento al usar enteros en lugares donde el código esperaba una cadena. Esto se corrigió en la v3.3.0. Una solución alternativa está disponible. Los usuarios que importan claves a través de un archivo JWK no deberían hacerlo de fuentes no confiables. Utilice la herramienta 'jwk2key' para verificar la validez de un archivo JWK. Asimismo, si es posible, no utilice archivos JWK con claves RSA-PSS."
    }
  ],
  "lastModified": "2026-06-17T10:38:24.333",
  "configurations": [
    {
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          "negate": false,
          "cpeMatch": [
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          "operator": "OR"
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}