Marimo has recently resolved a significant security vulnerability in its notebook software, which allowed unauthorized execution of Model Context Protocol (MCP) commands. This issue, documented by VulnCheck’s CVE Numbering Authority (CNA), posed a serious risk, enabling attackers to run commands in specially crafted notebooks.
Understanding the Vulnerability
The identified vulnerability, CVE-2026-75149, is a code injection problem affecting Marimo versions prior to 0.23.15. The flaw scored 8.7 on CVSS v4 and 8.8 on CVSS v3.1 due to its high severity. It required user interaction but did not necessitate authentication from the attacker. When a notebook was opened in edit mode, the malicious command could execute as a local subprocess before any notebook cell was run.
Resolution and Updates
Marimo addressed this vulnerability in version 0.23.15, released on July 23, 2026. The updated version ensures that users are safeguarded against the flaw, which was publicly disclosed on August 19. Users are advised to upgrade to a version beyond the affected range to mitigate potential risks.
To further protect against exploitation, Marimo implemented a PEP 723 hardening patch. This patch considers notebook metadata as potentially malicious, funneling configurations through a strict allowlist. Certain configurations, specifically related to AI and MCP, are removed to prevent unauthorized command execution.
Additional Security Measures
Moreover, the issue detailed in CVE-2026-75149 is distinct from other vulnerabilities previously identified in Marimo’s software. The company had earlier addressed another flaw, CVE-2026-67618, which involved unauthorized AI base URL configurations. This separate vulnerability also underscores the importance of strict security protocols within Marimo’s ecosystem.
Gregory Tan, known as Grg0rry, is credited with discovering CVE-2026-75149 and contributed to the development of Marimo’s PEP 723 hardening initiative. His work highlights the ongoing efforts to reinforce security across Marimo’s product lineup.
Marimo continues to prioritize user safety by providing security patches for the latest stable releases. It recommends users maintain updated software versions to ensure maximum protection against emerging threats.
