Patch Forecast
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CVE-2026-115921 · GHSA-m4pr-6v3c-6fgr

ONNX: Null Pointer Dereference in ScanInferenceFunction Due to Missing Required Attribute

Risk score
43/100
CVSS
6.2 v3.1
Exploit chance (30 days)
0.1%
Published
26 Oct 2026

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What to know

What it is
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 poin…
Affected
onnx (pip) >= 1.4.0, <= 1.21.0
Fix
Upgrade onnx to 1.22.0 or later.
Exploitation
No known exploitation

Story map

Story map: onnxTHE FLAWSTHE FIXCVE-2026-115921ONNX: Null Pointer Dereferencein ScanInferenceFunction Dueto Missing Required AttributeCVSS 6.2 · EPSS 0%CVE-2026-115922ONNX: Denial of service viaunchecked expansion of packedsub-byte tensors in ONNX…CVSS 6.2 · EPSS 0%CVE-2026-115919ONNX: Out-of-Bounds Read inRNN/GRU/LSTM ShapeInference (Old Opsets…CVSS 6.2 · EPSS 0%CVE-2026-115920ONNX: Out-of-bounds read inConvTranspose shape inferencevia undersized weight rankCVSS 6.2 · EPSS 0%Upgrade onnx1.22.0or later on your release lineWho is exposedonnx (pip) <= 1.21.0YELLOW · PLAN IT INonnxOpen Neural Network Exchange(ONNX) is an open standard formachine learninginteroperability. Prior to 1.22.0,_unpack_2bit() and_unpack_4bit() resize unpackedarrays according to…Where it standsNo known exploitationCONNECTS TOSame weaknessCWE-195 (CWE-195)8 other warnings in 30 days →
Story map: the flaws, the fix, how it unfolded and what it connects to. Boxes link to the record or article.

At a glance

onnx: Yellow, plan it in. Open Neural Network Exchange (ONNX) is an open standard for machine learning interoperability. Prior to 1.22.0, _unpack_2bit() and _unpack_4bit() resize unpacked arrays according to attacker-controlled TensorProto.dims without verifying that raw_data or int32_data encodes the declared number of elements. Materializing…

The flaws

  • CVE-2026-115921: ONNX: Null Pointer Dereference in ScanInferenceFunction Due to Missing Required Attribute (CVSS 6.2 · EPSS 0%)
  • CVE-2026-115922: ONNX: Denial of service via unchecked expansion of packed sub-byte tensors in ONNX Python APIs (CVSS 6.2 · EPSS 0%)
  • CVE-2026-115919: ONNX: Out-of-Bounds Read in RNN/GRU/LSTM Shape Inference (Old Opsets, Missing Rank Check) (CVSS 6.2 · EPSS 0%)
  • CVE-2026-115920: ONNX: Out-of-bounds read in ConvTranspose shape inference via undersized weight rank (CVSS 6.2 · EPSS 0%)

The fix

Upgrade onnx: 1.22.0 or later on your release line

Who is exposed: onnx (pip) <= 1.21.0

Where it stands

  • No known exploitation

Connects to

Why it is Yellow

  • CVSS 6.2 medium
  • On your watchlist: PyPI

Affected packages

PackageEcosystemVulnerableFixed in
onnxpip>= 1.4.0, <= 1.21.01.22.0

References

Original 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.

Last activity 28 Oct 2026. Patch Forecast updates every hour.