Low severity · published Aug 18, 2026
CVE-2026-63632
ONNX: Heap-Buffer-Overflow READ in Gemm Version Converter Adapter via Undersized Input Shape
3.3
CVSS
0.2%
EPSS
No
On KEV
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.
CVSS vector
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L
Attack vector
Local
Complexity
Low
Privileges
None
User interaction
Required
Confidentiality
None
Integrity
None
Availability
Low
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.2% · higher than 6% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
ON
onnx · onnx
>= 1.3.0, < 1.22.0 · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-63632
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-63632
github.com
https://github.com/onnx/onnx/commit/e9c74f596eaa0250f89e52a54160a25bbcb25b66
github.com
https://github.com/onnx/onnx/pull/7880
github.com
https://github.com/onnx/onnx/releases/tag/v1.22.0
github.com
https://github.com/onnx/onnx/security/advisories/GHSA-p893-rvq9-2xf9
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