Out-of-bounds Read in Onnx

CVE-2026-63632

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.

Vulnerability class: Buffer Overflow

Published · last modified .

CVSS v3 metric

CVSS v3 base score 3.3 (Low). Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L.

EPSS exploit prediction

EPSS: 0.002 (5.5th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 5th percentile — 5.5% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2026-63632: held from 0.002 to 0.002.

EPSS over last 30 days · oldest: 0.002 · newest: 0.002 · change: +0.000

Affected products

  • Onnx — versions >= 1.3.0, < 1.22.0

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-63632?
CVE-2026-63632 is a low-severity vulnerability in Onnx, classified under Out-of-bounds Read. CVSS score: 3.3/10. Published 2026-08-18.
How severe is CVE-2026-63632?
Low severity. CVSS v3 base score is 3.3 out of 10.