# CVE-2026-100845: MONAI unsafe deserialization in NumpyReader

Source: https://junglewise.ai/threats/cve-2026-100845-monai-before-1-6-0-contains-an-unsafe-deserialization  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-09-27. Updated: 2026-09-27  
License: CC BY 4.0 with a link back

CVE-2026-100845 · Severity: high · CVSS 7.8 · Published 2026-09-27

MONAI is a machine learning framework for medical imaging used by researchers and hospitals. Versions before 1.6.0 allow attackers to execute arbitrary code by crafting malicious .npy or .npz files that get loaded through MONAI's standard data pipeline. An attacker could poison shared datasets or tutorials to gain control of any machine running MONAI, potentially compromising sensitive patient data and hospital systems.

Technologies: [Project-MONAI MONAI](https://junglewise.ai/threats/technologies/project-monai-monai), [monai (PyPI)](https://junglewise.ai/threats/technologies/monai). Vendors: [Project-MONAI](https://junglewise.ai/threats/vendors/project-monai), [PyPI](https://junglewise.ai/threats/vendors/pypi).

## Quick answers

**Is CVE-2026-100845 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-100845 being exploited in the wild.

**How severe is CVE-2026-100845?** High severity, with a CVSS score of 7.8, published 27 September 2026.

**Which products and versions are affected?** Project-MONAI MONAI before 1.6.0; monai (PyPI) ECOSYSTEM:introduced=0,fixed=1.6.0.

**Is there a fix for CVE-2026-100845?** Yes. monai (PyPI): upgrade to 1.6.0 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-100845 attacked?** It is attacked with local access, in a software library.

**Am I affected by CVE-2026-100845?** Check whether you run Project-MONAI MONAI or monai (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

- monai (PyPI): upgrade to 1.6.0 or later

  ```sh
  pip install "monai>=1.6.0"
  ```


## Technical details

The NumpyReader class unconditionally calls numpy.load() with allow_pickle=True when reading .npy and .npz files, enabling arbitrary code execution via pickle deserialization. The vulnerability affects the entire MONAI data pipeline (LoadImage, PersistentDataset, CacheDataset, SmartCacheDataset) and the allow_pickle parameter is hardcoded and cannot be overridden by users. An attacker with the ability to control input .npy files can execute arbitrary code with the privileges of the MONAI process.

## Affected products

- Project-MONAI MONAI before 1.6.0

## Identifiers

- CVE-2026-100845
- GHSA-wg9g-w2j2-8pgr
- PYSEC-2026-4020

## Timeline

- 2026-06-11: disclosed
- 2026-09-26: advisory
- 2026-09-27: patched: Version 1.6.0 released

## References

- [https://github.com/Project-MONAI/MONAI/security/advisories/GHSA-wg9g-w2j2-8pgr](https://github.com/Project-MONAI/MONAI/security/advisories/GHSA-wg9g-w2j2-8pgr)
- [https://www.vulncheck.com/advisories/monai-before-1.6.0-remote-code-execution-via-numpyreader](https://www.vulncheck.com/advisories/monai-before-1.6.0-remote-code-execution-via-numpyreader)

## Related threats

- [MONAI MONAILabel server crash and inference corruption via crafted DICOM](https://junglewise.ai/threats/cve-2026-48705-monailabel-server-crash-and-silent-inference-corruption-via)
- [MONAI Auto3DSeg remote code execution via algo_from_json](https://junglewise.ai/threats/cve-2026-119578-monai-from-1-6-0-before-1-6-1-contains-a-remote-code-execution)
- [MONAI check_hash insufficient integrity verification](https://junglewise.ai/threats/cve-2026-118684-monai-before-1-6-1-contains-an-insufficient-integrity)
- [MONAI ConfigWorkflow remote code execution in logging.conf](https://junglewise.ai/threats/cve-2026-118683-monai-from-1-2-0-before-1-6-1-contains-a-remote-code-execution)
- [MONAI nnUNetV2Runner insecure deserialization in postprocessing](https://junglewise.ai/threats/cve-2026-109361-monai-1-2-0-before-1-6-1-contains-an-insecure-deserialization)