NULL pointer dereference in Onnx

CVE-2026-115921

Open Neural Network Exchange (ONNX) is an open standard for machine learning interoperability. From 1.4.0 until 1.22.0, ScanInferenceFunction, ScanInferenceFunction_opset8, and ScanInferenceFunction_opset9 do not safely validate the required num_scan_inputs attribute. A missing attribute is dereferenced as a null pointer, while a negative value is converted to size_t and can reach an exceptional oversized allocation path. An untrusted model can therefore terminate or disrupt shape inference, including a negative-value model that can pass onnx.checker.check_model(). This issue is fixed in version 1.22.0.

Published · last modified .

CVSS v3 metric

CVSS v3 base score 6.2 (Medium). Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

EPSS exploit prediction

No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.

Affected products

  • Onnx — versions >= 1.4.0, < 1.22.0

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-115921?
CVE-2026-115921 is a medium-severity vulnerability in Onnx, classified under CWE-195. CVSS score: 6.2/10. Published 2026-10-26.
How severe is CVE-2026-115921?
Medium severity. CVSS v3 base score is 6.2 out of 10.