What’s Vulnerable › Vulnerabilities

CVE-2026-39987: Marimo Remote Code Execution Vulnerability

• Severity: critical (CVSS 9.8 v3.1)
• Exploited in the wild: yes — in CISA KEV since 2026-04-23
• EPSS: 99.6% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2026-04-09 · updated 2026-06-17
• Weakness: CWE-306

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.

Affected products

• marimo-team marimo: before 0.23.0 — fixed in 0.23.0

How to fix

Upgrade to a fixed version: marimo-team marimo 0.23.0. Check the vendor advisory for mitigations.

References

• https://github.com/marimo-team/marimo/commit/c24d4806398f30be6b12acd6c60d1d7c68cfd12a
• https://github.com/marimo-team/marimo/pull/9098
• https://github.com/marimo-team/marimo/security/advisories/GHSA-2679-6mx9-h9xc
• https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-39987
• https://www.sysdig.com/blog/marimo-oss-python-notebook-rce-from-disclosure-to-exploitation-in-under-10-hours

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