CVE-2026-39987

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.

Affected products

Marimo

Coreweave Marimo

< 0.23.0

Fix

Available

CVSS 3.1

9.8 CRITICAL

EPSS

96.6% (100th percentile)

Weakness

CWE-306

NVD status

Analyzed

Published

2026-04-09