{"id":"CVE-2021-32677","state":"PUBLISHED","title":"Cross-Site Request Forgery (CSRF) in FastAPI","description":"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.","publishedAt":"2021-06-09T17:30:12.000Z","updatedAt":"2024-08-03T23:25:31.094Z","severity":{"score":8.2,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:N","source":"GitHub_M"},"assigner":"GitHub_M","products":["tiangolo fastapi"],"affected":[{"vendor":"tiangolo","product":"fastapi","versions":[{"version":"< 0.65.2","status":"affected"}]}],"references":["https://github.com/tiangolo/fastapi/security/advisories/GHSA-8h2j-cgx8-6xv7","https://github.com/tiangolo/fastapi/commit/fa7e3c996edf2d5482fff8f9d890ac2390dede4d","https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/MATAWX25TYKNEKLDMKWNLYDB34UWTROA/"],"weaknesses":["CWE-352"],"ingestedAt":"2026-10-29T19:48:33.225Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2021/32xxx/CVE-2021-32677.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.1","cveMetadata":{"cveId":"CVE-2021-32677","state":"PUBLISHED","datePublished":"2021-06-09T17:30:12.000Z","dateUpdated":"2024-08-03T23:25:31.094Z","assignerShortName":"GitHub_M","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateReserved":"2021-05-12T00:00:00.000Z"},"containers":{"cna":{"title":"Cross-Site Request Forgery (CSRF) in FastAPI","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'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."}],"affected":[{"vendor":"tiangolo","product":"fastapi","versions":[{"version":"< 0.65.2","status":"affected"}]}],"references":[{"url":"https://github.com/tiangolo/fastapi/security/advisories/GHSA-8h2j-cgx8-6xv7","tags":["x_refsource_CONFIRM"]},{"url":"https://github.com/tiangolo/fastapi/commit/fa7e3c996edf2d5482fff8f9d890ac2390dede4d","tags":["x_refsource_MISC"]},{"url":"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/MATAWX25TYKNEKLDMKWNLYDB34UWTROA/","name":"FEDORA-2021-917e89c036","tags":["vendor-advisory","x_refsource_FEDORA"]}],"metrics":[{"cvssV3_1":{"attackComplexity":"LOW","attackVector":"NETWORK","availabilityImpact":"NONE","baseScore":8.2,"baseSeverity":"HIGH","confidentialityImpact":"LOW","integrityImpact":"HIGH","privilegesRequired":"NONE","scope":"UNCHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:N","version":"3.1"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-352","description":"CWE-352: Cross-Site Request Forgery (CSRF)","lang":"en","type":"CWE"}]}],"providerMetadata":{"shortName":"GitHub_M","dateUpdated":"2021-06-18T02:06:14.000Z","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa"},"source":{"advisory":"GHSA-8h2j-cgx8-6xv7","discovery":"UNKNOWN"},"x_legacyV4Record":{"CVE_data_meta":{"ASSIGNER":"security-advisories@github.com","ID":"CVE-2021-32677","STATE":"PUBLIC","TITLE":"Cross-Site Request Forgery (CSRF) in FastAPI"},"affects":{"vendor":{"vendor_data":[{"product":{"product_data":[{"product_name":"fastapi","version":{"version_data":[{"version_value":"< 0.65.2"}]}}]},"vendor_name":"tiangolo"}]}},"data_format":"MITRE","data_type":"CVE","data_version":"4.0","description":{"description_data":[{"lang":"eng","value":"FastAPI is a web framework for building APIs with Python 3.6+ based on standard Python type hints. 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