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.

The detected version of the marimo Python package is prior to 0.23.0. It is, therefore, affected by a remote code execution 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     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.
    (CVE-2026-39987)

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

There are packages installed that are affected by a vulnerability referenced in the following CVE:

  - 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. (CVE-2026-39987)

ID	Name	Product	Family	Severity
310047	Python Library marimo < 0.23.0 Pre-Auth RCE (CVE-2026-39987)	Nessus	Misc.	critical
440087	SCA: security update for marimo (GHSA-2679-6mx9-h9xc)	Tenable Cloud Security	SCA Checks	critical
440087	SCA: security update for marimo (GHSA-2679-6mx9-h9xc)	Tenable Self-Hosted Container Security	SCA Checks	critical

Detections

Analytics

CVE-2026-39987

critical

Tenable Plugins

critical

critical

critical