# CVE-2026-44512: ONNX null pointer dereference in version_converter

Source: https://junglewise.ai/threats/cve-2026-44512-onnx-null-pointer-dereference-in-version-converter  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-07-08. Updated: 2026-07-08  
License: CC BY 4.0 with a link back

CVE-2026-44512 · Severity: medium · CVSS 5.5 · Published 2026-07-08

The Open Neural Network Exchange (ONNX) library, used for machine learning model interoperability, contains a flaw in its version conversion tool. An attacker can provide a specially crafted, malicious machine learning model that causes the software to crash when attempting to convert it between versions. This results in a denial-of-service, potentially disrupting model processing pipelines or automated deployment tools.

Technologies: [onnx (PyPI)](https://junglewise.ai/threats/technologies/onnx). Vendors: [PyPI](https://junglewise.ai/threats/vendors/pypi).

## Quick answers

**Is CVE-2026-44512 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-44512 being exploited in the wild.

**How severe is CVE-2026-44512?** Medium severity, with a CVSS score of 5.5, published 8 July 2026.

**Which products and versions are affected?** onnx (PyPI) >= 1.9.0, < 1.22.0, ECOSYSTEM:introduced=1.9.0,fixed=1.22.0.

**Is there a fix for CVE-2026-44512?** Yes. onnx (PyPI): upgrade to 1.22.0 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-44512 attacked?** It is attacked with local access, in a software library.

**Am I affected by CVE-2026-44512?** Check whether you run onnx (PyPI) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- onnx (PyPI): upgrade to 1.22.0 or later

  ```sh
  pip install "onnx>=1.22.0"
  ```


## Technical details

A NULL pointer dereference exists in the `onnx.version_converter.convert_version()` function, specifically within the `Upsample_6_7::adapt_upsample_6_7()` adapter in `onnx/version_converter/adapters/upsample_6_7.h`. The vulnerability is triggered when the converter processes an 'Upsample' node that has zero inputs, as the code attempts to access `node->inputs()[0]` without verifying the input count. In Release builds, bounds assertions are typically compiled out, leading to a SIGSEGV. An attacker can exploit this by providing a malformed model file to an application that performs version conversion. The issue is resolved in version 1.22.0 by adding explicit input/output bounds checks.

## Affected products

- onnx onnx >= 1.9.0, < 1.22.0

## Identifiers

- CVE-2026-44512
- GHSA-hwpq-hmq9-wj77
- PYSEC-2026-2689

## Timeline

- 2026-04-05: patched: Fix merged into main branch via PR #7813
- 2026-07-03: advisory: GHSA-hwpq-hmq9-wj77 published
- 2026-07-08: disclosed: CVE-2026-44512 published to NVD

## References

- [https://github.com/onnx/onnx/commit/cd310408165ad47c3cd7eb2b86cb5b80aa2e4fdf](https://github.com/onnx/onnx/commit/cd310408165ad47c3cd7eb2b86cb5b80aa2e4fdf)
- [https://github.com/onnx/onnx/pull/7813](https://github.com/onnx/onnx/pull/7813)
- [https://github.com/onnx/onnx/releases/tag/v1.22.0](https://github.com/onnx/onnx/releases/tag/v1.22.0)
- [https://github.com/onnx/onnx/security/advisories/GHSA-hwpq-hmq9-wj77](https://github.com/onnx/onnx/security/advisories/GHSA-hwpq-hmq9-wj77)

## Related threats

- [ONNX memory exhaustion in packed tensor unpacking](https://junglewise.ai/threats/cve-2026-115922-open-neural-network-exchange-onnx-is-an-open-standard-for)
- [ONNX null pointer dereference in shape inference](https://junglewise.ai/threats/cve-2026-115921-open-neural-network-exchange-onnx-is-an-open-standard-for)
- [ONNX ConvTranspose shape inference denial of service](https://junglewise.ai/threats/cve-2026-115920-open-neural-network-exchange-onnx-is-an-open-standard-for)
- [ONNX out-of-bounds read in RNN shape inference](https://junglewise.ai/threats/cve-2026-115919-open-neural-network-exchange-onnx-is-an-open-standard-for)
- [ONNX TOCTOU race condition in save_external_data](https://junglewise.ai/threats/onnx-toctou-race-condition-in-save-external-data-b85422b8)