Bug 2517918 (CVE-2026-63632)

Summary: CVE-2026-63632 onnx: ONNX: Denial of Service via out-of-bounds read in version converter
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
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Version: unspecifiedKeywords: Security
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OS: Linux   
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A flaw was found in Open Neural Network Exchange (ONNX). An out-of-bounds read can occur in the `onnx.version_converter.convert_version()` function when processing Gemm nodes with input tensors having fewer than two dimensions. This vulnerability, caused by a lack of rank checking, could allow an attacker to trigger a process crash during an opset 7 to 6 downgrade, leading to a Denial of Service (DoS).
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Description OSIDB Bzimport 2026-08-18 15:11:29 UTC 
Open Neural Network Exchange (ONNX) is an open standard for machine learning interoperability. From 1.3.0 until 1.22.0, onnx.version_converter.convert_version() can perform an out-of-bounds read in Gemm_7_6::adapt_gemm_7_6() in onnx/version_converter/adapters/gemm_7_6.h when a Gemm node has input tensors with fewer than two dimensions because B_shape[1], A_shape[0], or A_shape[1] is accessed without a rank check, potentially causing a process crash during an opset 7 to 6 downgrade. This issue is fixed in version 1.22.0.