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Fastapi-code-generator: Call-time RCE via operation summary -> unescaped route-handler docstring
Not on CISA's list of exploited flaws, and not in the news we track.
CVE-2026-63470Critical9.3
Black Shard's team can check your exposure to CVE-2026-63470 and take the fix off your plate.
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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Chance of exploitation in the next 30 days
0.47%
EPSS score from FIRST
Updated 13 Nov 2026, 12:01 UTC, 31 of 36 sources answering.
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