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CVE-2026-63471

9.3 criticalEPSS 0.3%

Critical (9.3). EPSS 0.3% estimated probability of exploitation activity in the next 30 days.

On this page
fastapi-code-generator creates FastAPI applications from OpenAPI files. Prior to 0.8.1, the generator inserts an OpenAPI path into a generated @app.get(...) route decorator as a single-quoted generated route string without escaping embedded quotes. An attacker-controlled or attacker-influenced OpenAPI path can close the string and inject a valid Python expression into the decorator argument. Syntax-breaking input only causes generation to fail, but syntactically valid generated code executes with the application's or CI process's privileges when the generated module is imported and the decorator is evaluated. This OpenAPI path sink is distinct from the project's separate operation-summary docstring and additional-response-key sinks. This issue is fixed in version 0.8.1.

Severity

CVSS 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
EPSS
0.3% estimated probability of exploitation activity in the next 30 days; 24th percentile. Scored 2026-11-04. A forecast for this CVE across the internet, not for your own systems.
CWEs
CWE-94 Improper Control of Generation of Code (Code Injection)
CWE-116 Improper Encoding or Escaping of Output
OWASP Top 10
A05:2025 Injection
Published
Modified
Record from
the NVD, synced

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Versions

From the CNA's record in the CVE List.

ProductAffected
koxudaxi fastapi-code-generator< 0.8.1

Attack patterns (CAPEC)

  • CAPEC-35 Leverage Executable Code in Non-Executable Files Likelihood: High · Severity: Very High
  • CAPEC-77 Manipulating User-Controlled Variables Likelihood: High · Severity: Very High
  • CAPEC-242 Code Injection Likelihood: High · Severity: High
  • CAPEC-73 User-Controlled Filename Likelihood: High · Severity: High
  • CAPEC-81 Web Server Logs Tampering Likelihood: Medium · Severity: High
  • CAPEC-85 AJAX Footprinting Likelihood: High · Severity: Low
  • CAPEC-104 Cross Zone Scripting Likelihood: Medium · Severity: High

The attack patterns MITRE's CAPEC relates to this record's weaknesses, as MITRE names them. Credits.

References

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