Low 3.3Published Aug 18, 2026

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

Updated under an hour ago (2026-10-19 10:00 UTC)

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No exploitation reported and no EPSS estimate yet.

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Exploited in the last 30 days

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.

CVSS: 3.3 LOW (v3.1, CNA)CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L
Weakness (CWE): CWE-125
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: GitHub_M
NVD analysis: Awaiting Analysis
Record last updated: Aug 18, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

onnx onnx onnx:onnx (from the name)	from 1.3.0, < 1.22.0	CNA record

References

https://github.com/onnx/onnx/security/advisories/GHSA-p893-rvq9-2xf9x-refsource-confirm
https://github.com/onnx/onnx/pull/7880x-refsource-misc
https://github.com/onnx/onnx/commit/e9c74f596eaa0250f89e52a54160a25bbcb25b66x-refsource-misc
https://github.com/onnx/onnx/releases/tag/v1.22.0x-refsource-misc

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.