Vulnerability details

CVE-2026-63470

koxudaxi fastapi-code-generator

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

CVSS 4.0
9.3Critical

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

ScoreVersionSourceVector
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

VendorProductVersionsSource
koxudaxi fastapi-code-generator < 0.8.1 CVEProject cvelistV5 (CNA)

References and advisories

4
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Details

Published
2026-11-03
Last updated
2026-11-03
State
Published
Assigner (CNA)
GitHub_M
Kolun priority
24 · Low

Exploit prediction (EPSS)

0.46%
Probability of exploitation in 30 days
40.7%
Percentile (among all CVEs)

SSVC assessment (CISA)

Automatable
Yes
Exploitation
Proof of concept
Technical impact
Total

Weaknesses (CWE)

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