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[ CVE-2026-39987 · Published 9 Apr 2026 ]

Marimo Remote Code Execution Vulnerability

Exploited · CISA KEV CVSS 9.8 EPSS 38%Fix available

[ Why it matters ]Priority signals

  • Exploited in the wild: on CISA's Known Exploited Vulnerabilities list since 2026-04-23
  • EPSS: 38% chance of exploitation in the next 30 days (higher than 99% of CVEs)
  • Critical severity: CVSS 9.8

[ Description ]Official description

marimo is a reactive Python notebook. Prior to 0.23.0, Marimo has a Pre-Auth RCE vulnerability. The terminal WebSocket endpoint /terminal/ws lacks authentication validation, allowing an unauthenticated attacker to obtain a full PTY shell and execute arbitrary system commands. 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. This vulnerability is fixed in 0.23.0.

CISA: Marimo contains an pre-authorization remote code execution vulnerability, allowing an unauthenticated attacked to shell access and execute arbitrary system commands.

[ Fixes ]Fixes and patches

CISA required action (US federal deadline 7 May 2026): Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.

[ References ]References