CVE-2026-115920: ONNX: Out-of-bounds read in ConvTranspose shape inference via undersized weight rank

Open Neural Network Exchange (ONNX) is an open standard for machine learning interoperability. From 1.2.1 until 1.22.0, ConvTranspose shape inference processes a weight tensor with fewer than three dimensions without a kernelshape attribute by deriving an empty effectivekernelshape and indexing it for the input's spatial dimensions. The flaw affects convTransposeShapeInferenceopset11() and the current inference path, and an untrusted model that can pass onnx.checker.checkmodel() can crash onnx.shapeinference.infershapes(), causing denial of service without demonstrated confidentiality or integrity impact. This issue is fixed in version 1.22.0.