# CVE-2026-100846: MONAI unsafe deserialization in algo_from_pickle

Source: https://junglewise.ai/threats/cve-2026-100846-monai-before-1-5-2-contains-a-deserialization-of-untrusted-data  
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-2026-100846 · Severity: high · CVSS 7.6 · Published 2026-09-27

MONAI is a medical imaging AI library used for automated 3D segmentation analysis. The algo_from_pickle function loads algorithm objects from pickle files without validation, allowing an attacker to craft a malicious pickle file that executes arbitrary code when loaded. An application using this function to process untrusted pickle files could be compromised with full system access.

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-2026-100846 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-100846 being exploited in the wild.

**How severe is CVE-2026-100846?** High severity, with a CVSS score of 7.6, published 27 September 2026.

**Which products and versions are affected?** Project-MONAI MONAI before 1.5.2; monai (PyPI) ECOSYSTEM:introduced=0,fixed=1.5.2.

**Is there a fix for CVE-2026-100846?** Yes. monai (PyPI): upgrade to 1.5.2 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-100846 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-100846?** 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 1.5.2 or later

  ```sh
  pip install "monai>=1.5.2"
  ```


## Technical details

The algo_from_pickle function in monai/auto3dseg/utils.py deserializes pickle data via pickle.loads() without validating input, enabling arbitrary code execution through __reduce__ gadgets. An attacker must supply a malicious .pkl file and the application must invoke algo_from_pickle on it; the exploit runs in the application's security context. A fix is available in MONAI 1.5.2.

## Affected products

- Project-MONAI MONAI before 1.5.2

## Identifiers

- CVE-2026-100846
- GHSA-89gg-p5r5-q6r4
- PYSEC-2026-4021

## Timeline

- 2026-09-27: disclosed
- 2026-04-03: patched: Version 1.5.2 released

## References

- [https://github.com/Project-MONAI/MONAI/security/advisories/GHSA-89gg-p5r5-q6r4](https://github.com/Project-MONAI/MONAI/security/advisories/GHSA-89gg-p5r5-q6r4)
- [https://www.vulncheck.com/advisories/monai-before-1.5.2-remote-code-execution-via-pickle-deserialization](https://www.vulncheck.com/advisories/monai-before-1.5.2-remote-code-execution-via-pickle-deserialization)

## 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)