CVE-2026-45365: Fastapi Internal Auth Bypass Flag As Query Param

FastAPI route handler `$FN` declares `$PARAM` as a plain primitive-typed function parameter. Because the parameter is a `bool`/`Optional[bool]` and is not wrapped in `Body(...)`, `Header(...)`, `Cookie(...)`, or `Depends(...)`, FastAPI binds it to the HTTP query string. An external caller can therefore append `?$PARAM=true` to the request URL and flip an int

Provally CuratedPublic repositoryHighHigh confidenceVerifiedApache-2.0python
greprules fetch cve-2026-45365-fastapi-internal-auth-bypass-flag-as-query-param --engine opengrep

Description

FastAPI route handler `$FN` declares `$PARAM` as a plain primitive-typed function parameter. Because the parameter is a `bool`/`Optional[bool]` and is not wrapped in `Body(...)`, `Header(...)`, `Cookie(...)`, or `Depends(...)`, FastAPI binds it to the HTTP query string. An external caller can therefore append `?$PARAM=true` to the request URL and flip an int

Detection target

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Recommended fix

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False-positive notes

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