CVE-2026-100846 MONAI before 1.5.2 Remote Code Execution via Pickle Deserialization

High 8.8 Published 27 Sep 2026 Updated 8 Oct 2026

Attackers can execute arbitrary code by supplying malicious pickle files to the algo_from_pickle function in MONAI.

Exploited in the wild: Not known
Login needed: An administrator
Attackable: Over the internet
Victim action needed: A user has to click or open something
Fix: Available

What is CVE-2026-100846?

CVE-2026-100846 is a high-severity unsafe deserialization vulnerability in Project-MONAI MONAI, published on 27 Sep 2026. An attacker needs administrator access to exploit it, and only if a user opens a file or follows a link.

Official description

MONAI before 1.5.2 contains a deserialization of untrusted data vulnerability in the algo_from_pickle function in monai/auto3dseg/utils.py. The function reads a .pkl file and passes its contents to pickle.loads without validating the data source or content. If an application invokes algo_from_pickle on an attacker-supplied pickle file, an object defining __reduce__ is executed during deserialization, resulting in arbitrary code execution in the context of the application.

Weakness: CWE-502

Which versions are affected by CVE-2026-100846?

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

Package	Affected	Fixed in
`monai` PyPI	All versions	`1.5.2`
`monai` PyPI	All versions	`1.6.0`
`monai` PyPI	All versions	`1.6.0`

Products include Project-Monai Monai.

How do I fix CVE-2026-100846?

Upgrade monai to a fixed version for your release line: 1.5.2 or 1.6.0.

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

Is CVE-2026-100846 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-100846 exists.

Sources

Also known as GHSA-89gg-p5r5-q6r4, GHSA-cvqf-4876-w239, PYSEC-2026-4021.