Axios: HTTP adapter streamed uploads bypass maxBodyLength when maxRedirects: 0

Axios is a promise based HTTP client for the browser and Node.js. Prior to 1.15.1 and 0.31.1, for stream request bodies, maxBodyLength is bypassed when maxRedirects is set to 0 (native http/https transport path). Oversized streamed uploads are sent fully even when the caller sets strict body limits. This vulnerability is fixed in 1.15.1 and 0.31.1.

Axios is a promise based HTTP client for the browser and Node.js. Prior to 1.15.1 and 0.31.1, for stream request bodies, maxBodyLength is bypassed when maxRedirects is set to 0 (native http/https transport path). Oversized streamed uploads are sent fully even when the caller sets strict body limits. This vulnerability is fixed in 1.15.1 and 0.31.1.

Axios is a promise based HTTP client for the browser and Node.js. Prior to 1.15.1 and 0.31.1, for stream request bodies, maxBodyLength is bypassed when maxRedirects is set to 0 (native http/https transport path). Oversized streamed uploads are sent fully even when the caller sets strict body limits. This vulnerability is fixed in 1.15.1 and 0.31.1.

### Summary For stream request bodies, maxBodyLength is bypassed when maxRedirects is set to 0 (native http/https transport path). Oversized streamed uploads are sent fully even when the caller sets strict body limits. ### Details Relevant flow in lib/adapters/http.js: - 556-564: maxBodyLength check applies only to buffered/non-stream data. - 681-682: maxRedirects === 0 selects native http/https transport. - 694-699: options.maxBodyLength is set, but native transport does not enforce it. - 925-945: stream is piped directly to socket (data.pipe(req)) with no Axios byte counting. This creates a path-specific bypass for streamed uploads. ### PoC Environment: - Axios main at commit f7a4ee2 - Node v24.2.0 Steps: 1. Start an HTTP server that counts uploaded bytes and returns {received}. 2. Send a 2 MiB Readable stream with: - adapter: 'http' - maxBodyLength: 1024 - maxRedirects: 0 Observed: - Request succeeds; server reports received: 2097152. Control checks: - Same stream with default/nonzero redirects: rejected with ERR_FR_MAX_BODY_LENGTH_EXCEEDED. - Buffered body with maxRedirects: 0: rejected with ERR_BAD_REQUEST. ### Impact Type: DoS / uncontrolled upstream upload / resource exhaustion. Impacted: Node.js services using streamed request bodies with maxBodyLength expecting hard enforcement, especially when following Axios guidance to use maxRedirects: 0 for streams.