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CVE-2017-11424

Estado: ModificadaAlta (7.5)—

In PyJWT 1.5.0 and below the `invalid_strings` check in `HMACAlgorithm.prepare_key` does not account for all PEM encoded public keys. Specifically, the PKCS1 PEM encoded format would be allowed because it is prefaced with the string `-----BEGIN RSA PUBLIC KEY-----` which is not accounted for. This enables symmetric/asymmetric key confusion attacks against users using the PKCS1 PEM encoded public keys, which would allow an attacker to craft JWTs from scratch.

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 (2)

Debian — Debian LinuxPyjwt Project — Pyjwt

CWE

Referencias

JSON original (NVD)

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{
  "id": "CVE-2017-11424",
  "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
      }
    ],
    "cvssMetricV30": [
      {
        "type": "Primary",
        "source": "nvd@nist.gov",
        "cvssData": {
          "scope": "UNCHANGED",
          "version": "3.0",
          "baseScore": 7.5,
          "attackVector": "NETWORK",
          "baseSeverity": "HIGH",
          "vectorString": "CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N",
          "integrityImpact": "HIGH",
          "userInteraction": "NONE",
          "attackComplexity": "LOW",
          "availabilityImpact": "NONE",
          "privilegesRequired": "NONE",
          "confidentialityImpact": "NONE"
        },
        "impactScore": 3.6,
        "exploitabilityScore": 3.9
      }
    ]
  },
  "affected": [
    {
      "source": "security@duo.com",
      "affectedData": [
        {
          "vendor": "n/a",
          "product": "n/a",
          "versions": [
            {
              "status": "affected",
              "version": "n/a"
            }
          ]
        }
      ]
    }
  ],
  "published": "2017-08-24T16:29:00.197",
  "references": [
    {
      "url": "http://www.debian.org/security/2017/dsa-3979",
      "tags": [
        "Third Party Advisory"
      ],
      "source": "security@duo.com"
    },
    {
      "url": "https://github.com/jpadilla/pyjwt/pull/277",
      "tags": [
        "Issue Tracking",
        "Patch",
        "Third Party Advisory"
      ],
      "source": "security@duo.com"
    },
    {
      "url": "http://www.debian.org/security/2017/dsa-3979",
      "tags": [
        "Third Party Advisory"
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      "source": "af854a3a-2127-422b-91ae-364da2661108"
    },
    {
      "url": "https://github.com/jpadilla/pyjwt/pull/277",
      "tags": [
        "Issue Tracking",
        "Patch",
        "Third Party Advisory"
      ],
      "source": "af854a3a-2127-422b-91ae-364da2661108"
    }
  ],
  "vulnStatus": "Modified",
  "weaknesses": [
    {
      "type": "Primary",
      "source": "nvd@nist.gov",
      "description": [
        {
          "lang": "en",
          "value": "NVD-CWE-noinfo"
        }
      ]
    }
  ],
  "descriptions": [
    {
      "lang": "en",
      "value": "In PyJWT 1.5.0 and below the `invalid_strings` check in `HMACAlgorithm.prepare_key` does not account for all PEM encoded public keys. Specifically, the PKCS1 PEM encoded format would be allowed because it is prefaced with the string `-----BEGIN RSA PUBLIC KEY-----` which is not accounted for. This enables symmetric/asymmetric key confusion attacks against users using the PKCS1 PEM encoded public keys, which would allow an attacker to craft JWTs from scratch."
    },
    {
      "lang": "es",
      "value": "En PyJWT 1.5.0 y anteriores, la comprobación `invalid_strings` en `HMACAlgorithm.prepare_key` no da cuenta de todas las claves públicas codificadas PEM. Específicamente, el formato codificado PKCS1 PEM se permitiría porque va precedido por la cadena `-----BEGIN RSA PUBLIC KEY-----`, la cual no se tiene en cuenta. Esto permite ataques simétricos/asimétricos de confusión de claves contra usuarios que empleen las claves públicas PKCS1 PEM, que permitirían que un atacante manipulase JWT desde cero."
    }
  ],
  "lastModified": "2026-06-17T01:01:47.717",
  "configurations": [
    {
      "nodes": [
        {
          "negate": false,
          "cpeMatch": [
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              "criteria": "cpe:2.3:a:pyjwt_project:pyjwt:*:*:*:*:*:*:*:*",
              "vulnerable": true,
              "matchCriteriaId": "2ED2491D-3EA6-4348-BABC-A1752F717260",
              "versionEndIncluding": "1.5.0"
            }
          ],
          "operator": "OR"
        }
      ]
    },
    {
      "nodes": [
        {
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          "cpeMatch": [
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            },
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              "vulnerable": true,
              "matchCriteriaId": "DEECE5FC-CACF-4496-A3E7-164736409252"
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          "operator": "OR"
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  ],
  "sourceIdentifier": "security@duo.com"
}