Vulnerability · Published Aug 18, 2026 · Assigned by GitHub_M
CVE-2026-63632ONNX: Heap-Buffer-Overflow READ in Gemm Version Converter Adapter via Undersized Input Shape
Low 3.3
In plain English
A low-severity out-of-bounds read in onnx from onnx. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 6% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:12 | onnx | no fix listed | DEBIAN-CVE-2026-63632 |
| Debian:13 | onnx | no fix listed | DEBIAN-CVE-2026-63632 |
| Debian:14 | onnx | no fix listed | DEBIAN-CVE-2026-63632 |
| PyPI | onnx | 1.22.0 | PYSEC-2026-3587 |
| PyPI | onnx | 1.22.0 | GHSA-p893-rvq9-2xf9 |
| Ubuntu:22.04:LTS | onnx | no fix listed | UBUNTU-CVE-2026-63632 |
| Ubuntu:26.04:LTS | onnx | no fix listed | UBUNTU-CVE-2026-63632 |
| Ubuntu:26.10 | onnx | no fix listed | UBUNTU-CVE-2026-63632 |
Affected products (as reported)
Weakness: CWE-125 · Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L
References
- https://github.com/onnx/onnx/security/advisories/GHSA-p893-rvq9-2xf9 x_refsource_CONFIRM
- https://github.com/onnx/onnx/pull/7880 x_refsource_MISC
- https://github.com/onnx/onnx/commit/e9c74f596eaa0250f89e52a54160a25bbcb25b66 x_refsource_MISC
- https://github.com/onnx/onnx/releases/tag/v1.22.0 x_refsource_MISC