MONAI has Path Traversal (Zip Slip) in NGC Private Bundle Download

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

5.3 · CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:H/A:N

EPSS

• CVE-2026-21851: 0.36% estimated exploitation activity in the next 30 days; percentile 29.56 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary A Path Traversal (Zip Slip) vulnerability exists in MONAI's downloadfromngcprivate() function. The function uses zipfile.ZipFile.extractall() without path validation, while other similar download functions in the same codebase properly use the existing safeextractmember() function. This appears to be an implementation oversight, as safe extraction is already implemented and used elsewhere in MONAI. CWE: CWE-22 (Improper Limitation of a Pathname to a Restricted Directory) --- Details Vulnerable Code Location File: monai/bundle/scripts.py Lines: 291-292 Function: downloadfromngcprivate() Root Cause The code calls z.extractall(extractpath) directly without validating that archive member paths stay within the extraction directory. Safe Code Already Exists MONAI already has a safe extraction function in monai/apps/utils.py (lines 125-154) that properly validates paths: Comparison with Other Download Functions | Function | File | Uses Safe Extraction? |…

Published by the source

6 Jan 2026, 17:32 UTC

Last modified by the source

7 Jul 2026, 17:56 UTC

Source last checked

26 Oct 2026, 13:36 UTC

1. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-9rg3-9pvr-6p27

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-9rg3-9pvr-6p27

Preview the exact text before you copy it. Commands are read-only suggestions; review them before running anything.

# Patch Next advisory brief: CVE-2026-21851

Advisory: MONAI has Path Traversal (Zip Slip) in NGC Private Bundle Download
IDs: CVE-2026-21851, GHSA-9rg3-9pvr-6p27
Record: https://patchnext.com/advisories/cve-2026-21851 (revision 2, source checked 26 Oct 2026, 13:36 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 5.3)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: monai 1.5.2. A vendor fix does not mean a deployment is fixed.

## Affected components
- PyPI monai: affected <= 1.5.1; fixed in 1.5.2

## Suggested inspection (read-only)
- `python -m pip show monai`: prints the installed version. Run with the environment that serves production active.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on monai.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-9rg3-9pvr-6p27 (OSV record GHSA-9rg3-9pvr-6p27 lists affected ranges: PyPI monai >=0 <1.5.2 (fixed))
- Verified: https://github.com/advisories/GHSA-9rg3-9pvr-6p27 (GitHub-reviewed advisory GHSA-9rg3-9pvr-6p27 lists affected ranges: PyPI monai >=0 <=1.5.1)

Commands are suggestions: review each one before running it.