ikkebr/tensorizer-cwe835-poc

⚠️ Tensorizer CWE-835 PoC — DO NOT LOAD IN PRODUCTION

Proof-of-concept files for an infinite-loop DoS in coreweave/tensorizer ≤ 2.12.1. Submitted to the vendor via huntr.com Model File Format program.

Loading loop.tensors with TensorDeserializer will hang the process at 100% CPU.

Files

file	effect
loop.tensors	Infinite read/seek loop in _copy_thread (serialization.py:3076-3093)
evil.tensors	Object-dtype PyObject* type-confusion primitive (_NumpyTensor.py:169); currently gated by torch.from_numpy
poc_infinite_loop.py	Generates loop.tensors and demonstrates the hang
poc_object_dtype.py	Generates evil.tensors and demonstrates the primitive

Repro

pip install tensorizer==2.12.1 torch --index-url https://download.pytorch.org/whl/cpu
python poc_infinite_loop.py
# → [PASS] PoC SUCCESS: TensorDeserializer hung >8s

Root cause

Signed <q data_length + independent metadata/header name fields → file_.seek(negative, SEEK_CUR) rewinds to the same header inside while tensors_read < len(tensor_items) where the counter only increments on name match.