Marimo RCE Flaw CVE-2026-39987 Exploited Within 10 Hours of Disclosure
Apr 10, 2026
Vulnerability / Threat Intelligence
A critical security vulnerability in Marimo , an open-source Python notebook for data science and analysis, has been exploited within 10 hours of public disclosure, according to findings from Sysdig. The vulnerability in question is CVE-2026-39987 (CVSS score: 9.3), a pre-authenticated remote code execution vulnerability impacting all versions of Marimo prior to and including 0.20.4. The issue has been addressed in version 0.23.0 . "The terminal WebSocket endpoint /terminal/ws lacks authentication validation, allowing an unauthenticated attacker to obtain a full PTY shell and execute arbitrary system commands," Marimo maintainers said in an advisory earlier this week. "Unlike other WebSocket endpoints (e.g., /ws) that correctly call validate_auth() for authentication, the /terminal/ws endpoint only checks the running mode and platform support before accepting connections, completely skipping authentication verification." In other words, at...