# CVE-2026-39987

## Summary

- **CVE ID:** CVE-2026-39987
- **Severity:** CRITICAL
- **CVSS Score:** 9.3 (CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N)
- **CWE:** CWE-306
- **Published:** Apr 9, 2026
- **Last Modified:** Apr 24, 2026

## 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 (< 0.23.0)

## References

- [CNA](https://github.com/marimo-team/marimo/security/advisories/GHSA-2679-6mx9-h9xc)
- [CNA](https://github.com/marimo-team/marimo/pull/9098)
- [CNA](https://github.com/marimo-team/marimo/commit/c24d4806398f30be6b12acd6c60d1d7c68cfd12a)
- [CISA-ADP](https://www.sysdig.com/blog/marimo-oss-python-notebook-rce-from-disclosure-to-exploitation-in-under-10-hours)
- [CISA-ADP](https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2025-39987)
- [CISA-ADP](https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-39987)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 98.95%
- **EPSS Percentile:** 99.9

## Known Exploited Vulnerabilities (KEV)

- **Date Added:** Apr 23, 2026
- **Due Date:** May 7, 2026

---
_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-10._