---
id: "CVE-2026-63470"
kind: "vulnerability"
aliases: ["CVE-2026-63470"]
title: "fastapi-code-generator: OpenAPI summaries inject Python code into generated handlers"
severity: "critical"
cvss: 9.3
epss: null
exploited: false
status: "open"
category: "package"
products: []
ecosystems: []
tags: ["code-generation", "fastapi", "openapi", "package", "python"]
not_affected_if: ["no-generator-use", "trusted-openapi-only", "version-0.8.1-or-later"]
published_at: "2026-11-03T20:18:15+00:00"
first_seen_at: "2026-11-03T20:49:22+00:00"
updated_at: "2026-11-03T20:49:44+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-63470", "first_seen_at": "2026-11-03T20:49:22+00:00"}]
---

# fastapi-code-generator: OpenAPI summaries inject Python code into generated handlers

fastapi-code-generator turns OpenAPI files into FastAPI applications and, before 0.8.1, pasted each operation's summary into a handler docstring without escaping embedded triple quotes. An attacker who controls or influences a summary can break out of the docstring and get injected Python that runs with the server's privileges when the route is called.

_Summary, check and fix written by a model from the sources; labelled as such._

## How to check

- Check the installed version of fastapi-code-generator with `pip show fastapi-code-generator` or `pip freeze | grep fastapi-code-generator`.
- Find the generated FastAPI route handlers and review whether any were generated from OpenAPI files with summaries you do not control.

## Fix

- fastapi-code-generator: move to `0.8.1` or later.

## Timeline

- 2026-11-03T20:49:22+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-63470

## Documents

- [advisory] Vendor advisory: github.com https://github.com/koxudaxi/fastapi-code-generator/security/advisories/GHSA-h667-4jj2-cgv4
- [fix] Patch: github.com https://github.com/koxudaxi/fastapi-code-generator/commit/49301dbdb82170d7f50877419d994b05cb1fa2bc
- [fix] Patch: github.com https://github.com/koxudaxi/fastapi-code-generator/commit/b3b9bd66e0b0c4d8c686fda700258104615a1332
- [fix] Release notes: github.com https://github.com/koxudaxi/fastapi-code-generator/releases/tag/0.8.1

## From the sources

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.

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