CVE-2026-63470
fastapi-code-generator: Call-time RCE via operation summary -> unescaped route-handler docstring
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.
Fixes and workarounds
No remediation reported in collected sources.
Missing remediation information is not evidence that no patch exists.
Affected products and versions
| Product | Versions | Authority |
|---|---|---|
| fastapi-code-generator koxudaxi |
< 0.8.1 (affected) | CNA: GitHub_M |
Version ranges are source assertions. Check the vendor advisory and your installed configuration before determining exposure.
CVSS assessments
| Version / score | Vector | Authority |
|---|---|---|
| 4.0 / 9.3 critical |
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N | CNA: GitHub_M |
Exploit evidence
- https://github.com/koxudaxi/fastapi-code-generator/security/advisories/GHSA-h667-4jj2-cgv4
exploit · ADP: CISA-ADP
References
- https://github.com/koxudaxi/fastapi-code-generator/security/advisories/GHSA-h667-4jj2-cgv4CNA: GitHub_M · x_refsource_CONFIRM
- https://github.com/koxudaxi/fastapi-code-generator/commit/49301dbdb82170d7f50877419d994b05cb1fa2bcCNA: GitHub_M · x_refsource_MISC
- https://github.com/koxudaxi/fastapi-code-generator/commit/b3b9bd66e0b0c4d8c686fda700258104615a1332CNA: GitHub_M · x_refsource_MISC
- https://github.com/koxudaxi/fastapi-code-generator/releases/tag/0.8.1CNA: GitHub_M · x_refsource_MISC
- https://github.com/koxudaxi/fastapi-code-generator/security/advisories/GHSA-h667-4jj2-cgv4ADP: CISA-ADP · exploit
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