On May 12, 2026, Microsoft Threat Intelligence along with security firms (Aikido, Wiz, Socket, and others) disclosed that mistralai==2.4.6 on PyPI contained malicious code. This was the official Python client library for Mistral AI's large language models.

The malicious version remained live for only a few hours but may have been downloaded by thousands of developers working on AI agents, trading bots, smart contract tools, RAG pipelines, and internal applications.

Key facts:

Only version 2.4.6 was affected. All other versions are clean.

The package has been removed from PyPI.

This attack is part of the ongoing "Mini Shai-Hulud" campaign that has already compromised many popular packages across PyPI and npm.

How the Malware Worked (Technical Breakdown)

The attack was stealthy and effective:

Execution on Import Malicious code was injected into src/mistralai/client/ init .py.…