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              "introduced": "0"
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    "CVE-2021-32677"
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    "cwe_ids": [
      "CWE-352"
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    "github_reviewed": true,
    "github_reviewed_at": "2021-06-09T13:34:54Z",
    "nvd_published_at": "2021-06-09T18:15:00Z",
    "severity": "HIGH"
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  "details": "### Impact\n\nFastAPI 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.\n\nIn 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`).\n\nSo, a request with a content type of `text/plain` containing JSON data would be accepted and the JSON data would be extracted.\n\nBut requests with content type `text/plain` are exempt from [CORS](https://developer.mozilla.org/en-US/docs/Web/HTTP/CORS) preflights, for being considered [Simple requests](https://developer.mozilla.org/en-US/docs/Web/HTTP/CORS#simple_requests). So, the browser would 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.\n\n### Patches\n\nThis is fixed in FastAPI `0.65.2`.\n\nThe 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`.\n\n### Workarounds\n\nIt\u0027s best to upgrade to the latest FastAPI.\n\nBut still, it would be possible to add 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.\n\n### References\n\n* [CORS on Mozilla web docs](https://developer.mozilla.org/en-US/docs/Web/HTTP/CORS)\n* [This answer on StackExchange](https://security.stackexchange.com/questions/157528/ways-to-bypass-browsers-cors-policy/157531#157531)\n* [OWASP CSRF](https://owasp.org/www-community/attacks/csrf)\n* Fixed in PR [#2118](https://github.com/tiangolo/fastapi/pull/2118)\n\n### For more information\n\nIf you have any questions or comments, write to [security@tiangolo.com](mailto:security@tiangolo.com)",
  "id": "GHSA-8h2j-cgx8-6xv7",
  "modified": "2024-09-20T17:18:26Z",
  "published": "2021-06-10T15:43:54Z",
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      "url": "https://github.com/tiangolo/fastapi/security/advisories/GHSA-8h2j-cgx8-6xv7"
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      "url": "https://github.com/pypa/advisory-database/tree/main/vulns/fastapi/PYSEC-2021-100.yaml"
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  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:N",
      "type": "CVSS_V3"
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      "type": "CVSS_V4"
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  ],
  "summary": "Cross-Site Request Forgery (CSRF) in FastAPI"
}

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