---
id: CVE-2026-63470
title: >-
  fastapi-code-generator: Call-time RCE via operation summary -> unescaped
  route-handler docstring
summary: >-
  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 qu…
severity: critical
cvss: 9.3
cvssVector: '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'
cvssSource: cna
cwe:
  - CWE-94
  - CWE-116
vendor: koxudaxi
product: fastapi-code-generator
affected:
  - fastapi-code-generator < 0.8.1
ssvc:
  exploitation: poc
  automatable: 'yes'
  technicalImpact: total
  timestamp: '2026-11-03T19:34:23.694611Z'
exploitAvailable: true
published: '2026-11-03'
updated: '2026-11-03'
sourceUpdated: '2026-11-03T19:34:47.499Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-63470'
references:
  - url: >-
      https://github.com/koxudaxi/fastapi-code-generator/security/advisories/GHSA-h667-4jj2-cgv4
    label: >-
      https://github.com/koxudaxi/fastapi-code-generator/security/advisories/GHSA-h667-4jj2-cgv4
  - url: >-
      https://github.com/koxudaxi/fastapi-code-generator/commit/49301dbdb82170d7f50877419d994b05cb1fa2bc
    label: >-
      https://github.com/koxudaxi/fastapi-code-generator/commit/49301dbdb82170d7f50877419d994b05cb1fa2bc
  - url: >-
      https://github.com/koxudaxi/fastapi-code-generator/commit/b3b9bd66e0b0c4d8c686fda700258104615a1332
    label: >-
      https://github.com/koxudaxi/fastapi-code-generator/commit/b3b9bd66e0b0c4d8c686fda700258104615a1332
  - url: 'https://github.com/koxudaxi/fastapi-code-generator/releases/tag/0.8.1'
    label: 'https://github.com/koxudaxi/fastapi-code-generator/releases/tag/0.8.1'
tags:
  - cve.org
  - exploit-available
epss: 0.00468
epssPercentile: 0.40603
ingestedAt: '2026-11-05T20:33:06.397Z'
---

## Overview

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.

## Affected

- `fastapi-code-generator < 0.8.1`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.