Vulnerability  ·  2026-04-11

CVE-2026-39987: Marimo Pre-Auth RCE Exploited Within 10 Hours of Disclosure

VulnerabilityHigh impactCVE-2026-39987
A pre-authenticated remote code execution vulnerability in Marimo, a reactive Python notebook popular in AI/ML development. The terminal WebSocket endpoint /terminal/ws lacks authentication validation, allowing unauthenticated attackers to execute arbitrary commands on the server.
An attacker connects to the unprotected /terminal/ws WebSocket endpoint without authentication and executes arbitrary system commands. The Sysdig Threat Research Team observed the first exploitation attempt 9 hours 41 minutes after advisory publication, with attackers building exploits directly from the advisory.
Marimo versions ≤ 0.20.4. Compromised environments typically expose credentials for OpenAI, Anthropic, and Google LLM APIs, as well as broader AI infrastructure access.
Update to Marimo version 0.23.0 immediately. Audit any Marimo instances exposed to the network for signs of compromise. Rotate all API keys and credentials accessible from Marimo environments.
Sources
The Hacker News — Marimo RCE Flaw CVE-2026-39987 Exploited Within 10 HoursCSA Lab Space — Marimo Pre-Auth RCE: AI Development Toolchain Under AttackEndor Labs — Root in One Request: Marimo Critical Pre-Auth RCESecurity Affairs — CVE-2026-39987 Exploited in Hours
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