CVE-2026-100845 MONAI before 1.6.0 Remote Code Execution via NumpyReader

High 8.5 Published 27 Sep 2026 Updated 28 Sep 2026

Attackers can execute arbitrary code by crafting malicious .npy files loaded via MONAI's NumpyReader due to unsafe pickle deserialization.

Exploited in the wild: Not known
Login needed: Not needed
Attackable: Local or same network only
Victim action needed: A user has to click or open something
Fix: Available

What is CVE-2026-100845?

CVE-2026-100845 is a high-severity unsafe deserialization vulnerability in Project-MONAI MONAI, published on 27 Sep 2026. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.

Official description

MONAI before 1.6.0 contains an unsafe deserialization vulnerability in the NumpyReader class that unconditionally uses numpy.load with allow_pickle=True when loading .npy and .npz files. Attackers can craft malicious .npy files with pickle payloads that execute arbitrary code when loaded through MONAI's standard data pipeline.

Weakness: CWE-502

Which versions are affected by CVE-2026-100845?

3 open source packages ship an affected version, including monai. It affects 1 product.

Package	Affected	Fixed in
`monai` PyPI	All versions	`1.6.0`
`monai` PyPI	All versions	`1.6.0`
`monai` PyPI	All versions	`1.6.0`

Products include Project-Monai Monai.

How do I fix CVE-2026-100845?

Upgrade monai to 1.6.0 or later.

Upgrade, and only deserialise data from trusted sources or with an allow-list of types. More about Unsafe deserialization.

Is CVE-2026-100845 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-100845 exists.

Sources

Also known as GHSA-4jj3-3266-2688, GHSA-wg9g-w2j2-8pgr, PYSEC-2026-4020.