GHSA-qwqc-p3q8-wcg9: Langflow: Unauthenticated DoS through multipart form boundary file upload

Summary

Langflow's `/api/v1/files/upload/` endpoint processes multipart form data before any authentication check, so an unauthenticated attacker can send a request with an oversized run of hyphens after the boundary and make the server unusable for all users indefinitely. The attacker does not need a valid flow ID, since the server parses the body even when the path ID is random, and the request can be repeated at will.

Mitigation

Fixed in 1.0.19 via PR #3923. A `check_boundary` HTTP middleware validates the multipart boundary against `^[\w\-]{1,70}$` and rejects malformed requests with HTTP 422 before the body is parsed, and the upload endpoint gained an authentication and flow-ownership check (`get_current_active_user`, HTTP 403 on mismatch). Upgrade to 1.0.19 or later.

Affected packages in the Exposure Registry

Matched by package name and ecosystem. Each entry shows whether the package delegates to a language model and how many tracked packages depend on it.

• langflowPyPIReaches an LLM package through dependencies

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