fkie_cve-2021-32677
Vulnerability from fkie_nvd
Published
2021-06-09 18:15
Modified
2024-11-21 06:07
Summary
FastAPI is a web framework for building APIs with Python 3.6+ based on standard Python type hints. FastAPI versions lower than 0.65.2 that used cookies for authentication in path operations that received JSON payloads sent by browsers were vulnerable to a Cross-Site Request Forgery (CSRF) attack. In versions lower than 0.65.2, FastAPI would try to read the request payload as JSON even if the content-type header sent was not set to application/json or a compatible JSON media type (e.g. application/geo+json). A request with a content type of text/plain containing JSON data would be accepted and the JSON data would be extracted. Requests with content type text/plain are exempt from CORS preflights, for being considered Simple requests. The browser will execute them right away including cookies, and the text content could be a JSON string that would be parsed and accepted by the FastAPI application. This is fixed in FastAPI 0.65.2. The request data is now parsed as JSON only if the content-type header is application/json or another JSON compatible media type like application/geo+json. It's best to upgrade to the latest FastAPI, but if updating is not possible then a middleware or a dependency that checks the content-type header and aborts the request if it is not application/json or another JSON compatible content type can act as a mitigating workaround.
Impacted products
Vendor Product Version
tiangolo fastapi *
fedoraproject fedora 34



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  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "FastAPI is a web framework for building APIs with Python 3.6+ based on standard Python type hints. FastAPI versions lower than 0.65.2 that used cookies for authentication in path operations that received JSON payloads sent by browsers were vulnerable to a Cross-Site Request Forgery (CSRF) attack. In versions lower than 0.65.2, FastAPI would try to read the request payload as JSON even if the content-type header sent was not set to application/json or a compatible JSON media type (e.g. application/geo+json). A request with a content type of text/plain containing JSON data would be accepted and the JSON data would be extracted. Requests with content type text/plain are exempt from CORS preflights, for being considered Simple requests. The browser will execute them right away including cookies, and the text content could be a JSON string that would be parsed and accepted by the FastAPI application. This is fixed in FastAPI 0.65.2. The request data is now parsed as JSON only if the content-type header is application/json or another JSON compatible media type like application/geo+json. It\u0027s best to upgrade to the latest FastAPI, but if updating is not possible then a middleware or a dependency that checks the content-type header and aborts the request if it is not application/json or another JSON compatible content type can act as a mitigating workaround."
    },
    {
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      "value": "FastAPI es un framework web para construir APIs con Python versi\u00f3n 3.6+ basado en sugerencias de tipo est\u00e1ndar de Python. Las versiones de FastAPI inferiores a la 0.65.2 que usaban cookies para la autenticaci\u00f3n en las operaciones de ruta que recib\u00edan cargas \u00fatiles JSON enviadas por los navegadores eran vulnerables a un ataque de tipo Cross-Site Request Forgery (CSRF). En versiones inferiores a la 0.65.2, FastAPI intentaba leer la carga \u00fatil de la petici\u00f3n como JSON incluso si la encabezado content-type enviada no estaba configurada como application/json o un tipo de medio JSON compatible (por ejemplo, application/geo+json). Una petici\u00f3n con un tipo de contenido text/plain que contenga datos JSON ser\u00e1 aceptada y los datos JSON ser\u00e1n extra\u00eddos. Las peticiones con tipo de contenido text/plain est\u00e1n exentas de preflights CORS, por ser consideradas peticiones simples. El navegador las ejecutar\u00e1 de inmediato, incluyendo las cookies, y el contenido de texto podr\u00eda ser una cadena JSON que ser\u00eda analizada y aceptada por la aplicaci\u00f3n FastAPI. Esto se ha corregido en FastAPI 0.65.2. Ahora los datos de la petici\u00f3n se analizan como JSON s\u00f3lo si la encabezado content-type es application/json u otro tipo de medio compatible con JSON como application/geo+json. Es mejor actualizar a la \u00faltima FastAPI, pero si la actualizaci\u00f3n no es posible, entonces un middleware o una dependencia que compruebe la encabezado de tipo de contenido y aborte la petici\u00f3n si no es application/json u otro tipo de contenido compatible con JSON puede actuar como una soluci\u00f3n de mitigaci\u00f3n"
    }
  ],
  "id": "CVE-2021-32677",
  "lastModified": "2024-11-21T06:07:30.713",
  "metrics": {
    "cvssMetricV2": [
      {
        "acInsufInfo": false,
        "baseSeverity": "MEDIUM",
        "cvssData": {
          "accessComplexity": "MEDIUM",
          "accessVector": "NETWORK",
          "authentication": "NONE",
          "availabilityImpact": "NONE",
          "baseScore": 5.8,
          "confidentialityImpact": "PARTIAL",
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          "vectorString": "AV:N/AC:M/Au:N/C:P/I:P/A:N",
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        "impactScore": 4.9,
        "obtainAllPrivilege": false,
        "obtainOtherPrivilege": false,
        "obtainUserPrivilege": false,
        "source": "nvd@nist.gov",
        "type": "Primary",
        "userInteractionRequired": true
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        "impactScore": 5.2,
        "source": "nvd@nist.gov",
        "type": "Primary"
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  "published": "2021-06-09T18:15:08.553",
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      "source": "security-advisories@github.com",
      "tags": [
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      ],
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    },
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  "sourceIdentifier": "security-advisories@github.com",
  "vulnStatus": "Modified",
  "weaknesses": [
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          "value": "CWE-352"
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      ],
      "source": "security-advisories@github.com",
      "type": "Primary"
    }
  ]
}


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