CVE-2026-75149 is a code injection vulnerability in marimo versions prior to 0.23.15. The issue exists in the notebook configuration handler, where an attacker can supply a specially crafted MCP server entry containing an attacker-controlled command. When a user opens the notebook in edit mode, marimo executes the embedded command as a local subprocess before any notebook cell runs. This occurs without any authentication or user action beyond opening the notebook, enabling remote code execution on the local system.

Successful exploitation allows an unauthenticated attacker to execute arbitrary commands on the local system running marimo simply by having a user open a maliciously crafted notebook in edit mode. This can lead to full system compromise depending on the privileges of the marimo process. The vulnerability has a high CVSS 4.0 score of 8.7, reflecting its network attack vector, low attack complexity, no privileges required, and high impact on confidentiality, integrity, and availability.

Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Users should avoid opening untrusted notebooks in edit mode until an official fix is available. Monitor the vendor's channels for updates regarding patches or official mitigations.