CVE-2026-115921 ONNX: Null Pointer Dereference in ScanInferenceFunction Due to Missing Required Attribute
- Exploited in the wild
- Not known
- Fix
- Available
What is CVE-2026-115921?
CVE-2026-115921 is a medium-severity vulnerability in onnx, published on 26 Oct 2026.
Official description
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.
Which versions are affected by CVE-2026-115921?
2 open source packages ship an affected version, including onnx.
| Package | Affected | Fixed in |
|---|---|---|
onnx PyPI | From 1.4.0 | 1.22.0 |
onnx PyPI | From 1.4.0 | 1.22.0 |
How do I fix CVE-2026-115921?
Upgrade onnx to 1.22.0 or later.
Is CVE-2026-115921 being exploited?
There is no known exploitation of CVE-2026-115921 in the wild and no public exploit code.
Sources
Also known as DEBIAN-CVE-2026-115921, ECHO-7bdd-e92f-26f6, GHSA-m4pr-6v3c-6fgr, UBUNTU-CVE-2026-115921.