CVE-2026-115922: Denial of Service via Unchecked Expansion of Packed Sub-Byte Tensors in ONNX

Vulnerability ID: CVE-2026-115922

CVSS Score: 6.2

Published: 2026-10-28

Open Neural Network Exchange (ONNX) prior to version 1.22.0 contains a memory exhaustion vulnerability (CWE-789) in its Python tensor unpacking helpers and C++ model checker. Specifically, the _unpack_2bit() and _unpack_4bit() functions in onnx.numpy_helper unconditionally resize unpacked NumPy arrays to match attacker-controlled TensorProto.dims metadata without verifying that the underlying raw_data or int32_data buffers contain a corresponding number of packed bits. Furthermore, onnx.checker.check_tensor() previously bypassed length verification for sub-byte data types.…