CVE-2026-63469
fastapi-code-generator: Import-time RCE via response status-code key -> unescaped @app.get(..., responses={...}) dict
Published Nov 3, 2026
CVSS 4.0 · 9.3 Critical
EPSS < 1%
KEV · Not listed
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.
Affected Products
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CVE record
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NVD configurations
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Red Hat packages
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OpenCVE enrichment
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Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).
| Vendor | Product | Default status | Versions | ||||||
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| koxudaxi | fastapi-code-generator | affected |
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Remediation
Tracking
Advisories
| Source | ID | Title |
|---|---|---|
 Github GHSA |
GHSA-6xmv-cjr5-w3q8 | fastapi-code-generator: Import-time RCE via response status-code key -> unescaped @app.get(..., responses={...}) dict |
Metrics
Attack Vector Network
Attack Complexity Low
Privileges Required None
Attack Requirements None
User Interaction None
Vulnerable System Confidentiality Impact High
Vulnerable System Integrity Impact High
Vulnerable System Availability Impact High
Subsequent System Confidentiality Impact None
Subsequent System Integrity Impact None
Subsequent System Availability Impact None
No CVSS v3.1
No CVSS v3.0
No CVSS v2
This CVE is not in the KEV list.
Exploit prediction score: < 1% (0.312% probability within 30 days)
Exploitation poc
Automatable yes
Technical Impact total
References
History
Nov 10, 2026 9:30 PM
Scoring metrics updated
View changes
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| Metrics |
ssvc
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Nov 3, 2026 7:30 PM
Description updated. Title updated. Weaknesses updated. Added references. Scoring metrics updated
View changes
| Type | Values Removed | Values 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. | |
| Title | fastapi-code-generator: Import-time RCE via response status-code key -> unescaped @app.get(..., responses={...}) dict | |
| Weaknesses | CWE-116 CWE-94 |
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| Metrics |
cvssV4_0
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Subscriptions
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