CVE-2026-63469
fastapi-code-generator: Import-time RCE via response status-code key -> unescaped @app.get(..., responses={...}) dict
Description
fastapi-code-generator creates FastAPI applications from OpenAPI files. Prior to 0.8.1, the generator inserts an additional response status-code key into the generated responses={...} route-decorator dictionary as a single-quoted Python string without escaping embedded quotes. A multi-response OpenAPI operation with an attacker-controlled or attacker-influenced second non-primary response key can close the dictionary-key literal and inject a valid Python expression. 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 its decorator arguments are evaluated. This additional-response-key sink is distinct from the project's separate route-path and operation-summary sinks. This issue is fixed in version 0.8.1.
INFO
Published Date :
Nov. 3, 2026, 8:18 p.m.
Last Modified :
Nov. 3, 2026, 8:18 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
Affected Products
The following products are affected by CVE-2026-63469
vulnerability.
Even if cvefeed.io is aware of the exact versions of the
products
that
are
affected, the information is not represented in the table below.
No affected product recoded yet
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 4.0 | CRITICAL | [email protected] |
Solution
- Update fastapi-code-generator to version 0.8.1 or later.
- Review generated code for security issues.
- Avoid importing untrusted generated code.
- Validate OpenAPI specifications.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-63469.
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-63469 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-63469
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-63469 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-63469 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
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New CVE Received by [email protected]
Nov. 03, 2026
Action Type Old Value New Value Added Description fastapi-code-generator creates FastAPI applications from OpenAPI files. Prior to 0.8.1, the generator inserts an additional response status-code key into the generated responses={...} route-decorator dictionary as a single-quoted Python string without escaping embedded quotes. A multi-response OpenAPI operation with an attacker-controlled or attacker-influenced second non-primary response key can close the dictionary-key literal and inject a valid Python expression. 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 its decorator arguments are evaluated. This additional-response-key sink is distinct from the project's separate route-path and operation-summary sinks. This issue is fixed in version 0.8.1. Added CVSS V4.0 AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X Added CWE CWE-94 Added CWE CWE-116 Added Affected New affected value received. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/63xxx/CVE-2026-63469.json">CVE-2026-63469</a> Added Reference https://github.com/koxudaxi/fastapi-code-generator/commit/49301dbdb82170d7f50877419d994b05cb1fa2bc Added Reference https://github.com/koxudaxi/fastapi-code-generator/commit/b3b9bd66e0b0c4d8c686fda700258104615a1332 Added Reference https://github.com/koxudaxi/fastapi-code-generator/releases/tag/0.8.1 Added Reference https://github.com/koxudaxi/fastapi-code-generator/security/advisories/GHSA-6xmv-cjr5-w3q8