CVE-2026-63470

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CVE-2026-63470

Summary: fastapi-code-generator: Call-time RCE via operation summary -> unescaped route-handler docstring

Details: fastapi-code-generator creates FastAPI applications from OpenAPI files. Prior to 0.8.1, the generator inserts Operation.summary into a generated route-handler docstring as a triple-double-quoted string without escaping embedded triple quotes. An attacker-controlled or attacker-influenced operation summary can close the docstring and inject a valid Python expression statement into the handler body. Syntax-breaking input only causes generation to fail, but syntactically valid generated code executes with the server process's privileges when the affected route handler is called. This call-time route-handler docstring sink is distinct from the project's separate import-time route-path and additional-response-key sinks. This issue is fixed in version 0.8.1.

References: https://github.com/koxudaxi/fastapi-code-generator/releases/tag/0.8.1, https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/63xxx/CVE-2026-63470.json, https://github.com/koxudaxi/fastapi-code-generator/security/advisories/GHSA-h667-4jj2-cgv4, https://nvd.nist.gov/vuln/detail/CVE-2026-63470, https://github.com/koxudaxi/fastapi-code-generator/commit/49301dbdb82170d7f50877419d994b05cb1fa2bc, https://github.com/koxudaxi/fastapi-code-generator/commit/b3b9bd66e0b0c4d8c686fda700258104615a1332