runai-model-streamer header DoS — PoC model file

Security proof-of-concept for a Denial-of-Service in run-ai/runai-model-streamer (commit 5c83ddb). Reported via huntr's Model File Vulnerability program.

model.safetensors is a 78-byte safetensors file whose header omits the dtype key. Loading it through the public SafetensorsStreamer API crashes the parser with an uncaught KeyError, before any tensor data is read. This affects any app using runai-model-streamer, including vLLM started with --load-format runai_streamer.

Reproduce

pip install runai-model-streamer torch — no GPU required:

from runai_model_streamer.safetensors_streamer.safetensors_streamer import SafetensorsStreamer
with SafetensorsStreamer() as s:
s.stream_file("model.safetensors")
list(s.get_tensors())

-> KeyError: 'dtype' (uncaught -> loader crash)
Harmless file: it triggers an unhandled exception, not code execution.