CVE-2026-63470 PUBLISHED

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

Assigner: GitHub_M
Reserved: 16.07.2026 Published: 03.11.2026 Updated: 03.11.2026

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.

Metrics

CVSS Vector: 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
CVSS Score: 9.3

Product Status

Vendor koxudaxi
Product fastapi-code-generator
Versions
  • Version < 0.8.1 is affected

References

Problem Types

  • CWE-94: Improper Control of Generation of Code ('Code Injection') CWE
  • CWE-116: Improper Encoding or Escaping of Output CWE