April 23, 2026 · Applied Cybernetics Group
CVE-2026-39987 — Marimo Marimo
Marimo Remote Code Execution Vulnerability
- Added to KEV
2026-04-23- Federal due date
2026-05-07- Vendor
- Marimo
- Product
- Marimo
- EPSS
- 99.9th percentile (score 0.956, as of
2026-07-13) - NVD CVSS v3.1
- 9.8 (CRITICAL)
- Ransomware use
- Unknown
- Upstream
- https://nvd.nist.gov/vuln/detail/CVE-2026-39987
CISA short description
Marimo contains an pre-authorization remote code execution vulnerability, allowing an unauthenticated attacked to shell access and execute arbitrary system commands.
Required action
Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
NVD 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.