What is 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.
Timeline
- 2026-04-09Published to the U.S. National Vulnerability Database (NVD)
- 2026-04-11First covered in a defend.network daily briefing
- 2026-04-23Added to the CISA Known Exploited Vulnerabilities (KEV) catalog
- 2026-05-07CISA federal remediation deadline (BOD 22-01)
- 2026-06-17NVD record last updated
CISA Known Exploited Vulnerability
Marimo Remote Code Execution Vulnerability
Affected product
Coreweave Marimo
Remediation Steps
- Apply the vendor patch for Marimo immediately
- Audit internet-exposed Marimo notebook instances and restrict access to trusted networks
- Review access logs for unauthorized changes to notebooks or credential extraction
- Rotate all cloud credentials and API keys stored in or accessible via Marimo instances
- Implement network segmentation to isolate notebook environments from sensitive systems
References
- https://github.com/marimo-team/marimo/security/advisories/GHSA-2679-6mx9-h9xc
- https://github.com/marimo-team/marimo/commit/c24d4806398f30be6b12acd6c60d1d7c68cfd12a
- https://github.com/marimo-team/marimo/pull/9098
- https://nvd.nist.gov/vuln/detail/CVE-2026-39987
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog
Referenced in our briefings & reports
- Vulnerability Priority Report – Week 1 of June 2026 (June 1 – 7)
- Vulnerability Priority Report – Week 2 of April 2026 (April 13 – 19)
- ChatGPT malware abuse, Marimo CVE-2026-39987 LLM exploitation, Russian infrastructure arrests (2026-05-30)
- Iran PLC attacks; Marimo RCE exploited in 10h; GlassWorm IDE infection (2026-04-12)
- Marimo RCE exploited; Iran targets 4,000 US PLCs; Russian token theft (2026-04-11)
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🤖 This CVE page is generated by defend.network from NVD, CISA KEV, EPSS, and our verified daily briefings. Severity and exploitation data come from official sources; always verify remediation steps against the official vendor advisory before acting in production.