GHSA-5c9x-8gcm-mpgx
Axios' HTTP adapter-streamed uploads bypass maxBodyLength when maxRedirects: 0
Details
### 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.
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