CVE-2026-63632: ONNX: Heap-Buffer-Overflow READ in Gemm Version Converter Adapter via Undersized Input Shape

July 24, 2026

Heap-buffer-overflow READ (16 bytes) in Gemm_7_6::adapt_gemm_7_6() (onnx/version_converter/adapters/gemm_7_6.h:41) when ConvertVersion() processes a model with a Gemm node whose input tensors have fewer than 2 dimensions. The adapter accesses B_shape[1] without checking rank. On Release builds the OOB read is silent; ASan confirms 16-byte read past a 48-byte allocation.

References

github.com/advisories/GHSA-p893-rvq9-2xf9
github.com/onnx/onnx/commit/e9c74f596eaa0250f89e52a54160a25bbcb25b66
github.com/onnx/onnx/pull/7880
github.com/onnx/onnx/releases/tag/v1.22.0
github.com/onnx/onnx/security/advisories/GHSA-p893-rvq9-2xf9
nvd.nist.gov/vuln/detail/CVE-2026-63632

Code Behaviors & Features

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