Vulnerability details
CVE-2026-63470
fastapi-code-generator: Call-time RCE via operation summary -> unescaped route-handler docstring
Official description
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.
CVSS scores
| Score | Version | Source | Vector |
|---|---|---|---|
| 9.3Critical | 4.0 | CVEProject cvelistV5 (CNA) (GitHub_M) | 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 |
Affected products
| Vendor | Product | Versions | Source |
|---|---|---|---|
| koxudaxi | fastapi-code-generator | < 0.8.1 | CVEProject cvelistV5 (CNA) |
References and advisories
4- https://github.com/koxudaxi/fastapi-code-generator/commit/49301dbdb82170d7f50877419d994b05cb1fa2bc x_refsource_MISC
- https://github.com/koxudaxi/fastapi-code-generator/commit/b3b9bd66e0b0c4d8c686fda700258104615a1332 x_refsource_MISC
- https://github.com/koxudaxi/fastapi-code-generator/releases/tag/0.8.1 x_refsource_MISC
- https://github.com/koxudaxi/fastapi-code-generator/security/advisories/GHSA-h667-4jj2-cgv4 x_refsource_CONFIRM
Details
- Published
- 2026-11-03
- Last updated
- 2026-11-03
- State
- Published
- Assigner (CNA)
- GitHub_M
- Kolun priority
- 24 · Low
Exploit prediction (EPSS)
SSVC assessment (CISA)
- Automatable
- Yes
- Exploitation
- Proof of concept
- Technical impact
- Total
Weaknesses (CWE)
- CWE-94Improper Control of Generation of Code ('Code Injection')
- CWE-116Improper Encoding or Escaping of Output