GHSA-jqh4-m9w3-8hp9

## Summary axios’ fetch adapter does not enforce `maxBodyLength` for live WHATWG `ReadableStream` request bodies whose size cannot be determined before dispatch. Applications that use `adapter: "fetch"` and rely on `maxBodyLength` to cap untrusted upload/proxy streams can send the full stream even when it exceeds the configured limit. This affects fetch-adapter usage in edge runtimes where fetch is selected, and in Node.js or browser environments where the fetch adapter is explicitly selected. The HTTP adapter’s stream upload path is not affected. ## Impact An attacker who can supply or influence a streamed request body can bypass the caller’s configured upload-size limit. Practical impact is unexpected outbound network egress, request-level resource consumption, and possible exhaustion of upstream API quotas or bandwidth. This does not expose response data, execute code, or modify axios configuration. Exploitability depends on an application passing attacker-controlled, unknown-length stream data to axios and relying on `maxBodyLength` as the size guard. ## Affected Functionality Affected: - `adapter: "fetch"` or environments where axios selects the fetch adapter. - Request methods with bodies, such as `POST`, `PUT`, and `PATCH`. - `data` as a WHATWG `ReadableStream` without a reliable `Content-Length`. - Configurations that set `maxBodyLength` to a finite value. Not affected: - Axios versions before the fetch adapter was introduced. - The Node HTTP adapter stream enforcement path. - Known-length fetch-adapter bodies in `1.16.0+`, such as strings, `Blob`, `ArrayBuffer`, `ArrayBufferView`, URLSearchParams, spec-compliant FormData, or requests with a finite `Content-Length`. ## Technical Details In `lib/adapters/fetch.js`, `getBodyLength()` handles null bodies, `Blob`, spec-compliant FormData, ArrayBuffer values, URLSearchParams, and strings. It has no branch for `ReadableStream`, so `resolveBodyLength(headers, data)` returns `undefined` when no finite `Con