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

Affected: Project-MONAI MONAI

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.

GHSA-9rg3-9pvr-6p27 — MONAI has Path Traversal (Zip Slip) in NGC Private Bundle Download

Affected: PyPI: monai

## Summary

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.

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:** `_download_from_ngc_private()`

```python # monai/bundle/scripts.py - Lines 284-293 zip_path = download_path / f"{filename}_v{version}.zip" with open(zip_path, "wb") as f: f.write(response.content) logger.info(f"Downloading: {zip_path}.") if remove_prefix: filename = _remove_ngc_prefix(filename, prefix=remove_prefix) extract_path = download_path / f"{filename}" with zipfile.ZipFile(zip_path, "r") as z: z.extractall(extract_path) # <-- No path validation logger.info(f"Writing into directory: {extract_path}.") ```

### Root Cause

The code calls `z.extractall(extract_path)` 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:

```python def safe_extract_memb…

Most recent entries from all

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

GHSA-9rg3-9pvr-6p27 — MONAI has Path Traversal (Zip Slip) in NGC Private Bundle Download