CVE-2026-115922

Medium

Description

Open Neural Network Exchange (ONNX) is an open standard for machine learning interoperability. Prior to 1.22.0, _unpack_2bit() and _unpack_4bit() resize unpacked arrays according to attacker-controlled TensorProto.dims without verifying that raw_data or int32_data encodes the declared number of elements. Materializing an untrusted UINT2, INT2, UINT4, INT4, or FLOAT4E2M1 tensor through onnx.numpy_helper.to_array() or onnx.reference.ReferenceEvaluator can therefore expand a small packed payload into a disproportionately large allocation and exhaust memory. This issue is fixed in version 1.22.0.

SeverityMedium
CVSS6.2
Exploit probability—
ProductOnnx
PublishedOct 26, 2026
First seenOct 26, 2026
Weakness typeCWE-789CWE-789

How to fix

Update
  • onnx1.22.0 or later

Affected products

ProductAffected versionsFixed in
onnxPyPIv ≤ 1.21.01.22.0

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