---
title: "CVE-2026-39987: marimo Affected by Pre-Auth Remote Code… | CubePath"
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…"
language: en
source: https://cubepath.com/security/cve/CVE-2026-39987
---

# CVE-2026-39987: marimo Affected by Pre-Auth Remote Code… | CubePath

## 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.

Official description from the CVE record, published by GitHub\_M. Copyright © 1999-2026 The MITRE Corporation. See [/security/cve/legal](https://cubepath.com/security/cve/legal) for the CVE license. [View the record on cve.org](https://www.cve.org/CVERecord?id=CVE-2026-39987)

## Key data

### CVSS 4.0 Critical 9.3

Score published by GitHub\_M in the CVE record.

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

| Metric                              | Value   | What it means                                                                                                   |
| ----------------------------------- | ------- | --------------------------------------------------------------------------------------------------------------- |
| Attack vector                       | Network | The vulnerable component can be reached over a network, possibly from the Internet.                             |
| Attack complexity                   | Low     | No measurable action is needed to get around the system's built-in security controls. The attack is repeatable. |
| Attack requirements                 | None    | The attack works without any special deployment or execution conditions.                                        |
| Privileges required                 | None    | No account or privileges are needed.                                                                            |
| User interaction                    | None    | No action from any user is needed.                                                                              |
| Vulnerable system: confidentiality  | High    | Serious or total effect on the secrecy of data.                                                                 |
| Vulnerable system: integrity        | High    | Serious or total effect on the trustworthiness of data.                                                         |
| Vulnerable system: availability     | High    | Serious or total effect on availability.                                                                        |
| Subsequent systems: confidentiality | None    | No effect on other systems' data secrecy.                                                                       |
| Subsequent systems: integrity       | None    | No effect on other systems' data trustworthiness.                                                               |
| Subsequent systems: availability    | None    | No effect on other systems' availability.                                                                       |

CVSS is owned and managed by FIRST.Org, Inc. (FIRST) and is used by permission. Each CVSS score on this site is shown together with its vector string, as published in the CVE record by the source named next to it. Learn more at [first.org/cvss](https://www.first.org/cvss/) .

### EPSS

Exploit Prediction Scoring System by FIRST: an estimate of the probability that exploitation activity will be observed in the next 30 days.

Score

0.99743 (99.7% probability)

Percentile

99.95%

Scores of

Nov 10, 2026

Model

v2026.06.15

### CISA Known Exploited Vulnerabilities

This CVE is listed in the CISA KEV catalog.

Name in the catalog

Marimo Remote Code Execution Vulnerability

Added to the catalog

Apr 23, 2026

Federal due date

May 7, 2026

### CISA assessment as of Apr 23, 2026

Stakeholder-Specific Vulnerability Categorization (SSVC) decision points added by CISA.

Exploitation

Recorded by CISA as active

Automatable

yes

Technical impact

total

### Weakness (CWE)

CWE catalog version 5.0.

CWE names: Copyright © 2006-2026, The MITRE Corporation. See [/security/cve/legal](https://cubepath.com/security/cve/legal) for the CWE license.

- [CWE-306](https://cwe.mitre.org/data/definitions/306.html) Missing Authentication for Critical Functionality

## Affected products

Products listed in the CVE record, as the CNA published them.

- marimo-team marimo

  - affected: < 0.23.0

## References

Links listed in the CVE record. They lead to other sites, which CubePath does not control.

- [github.com/marimo-team/marimo/security/advisories/GHSA-2679…](https://github.com/marimo-team/marimo/security/advisories/GHSA-2679-6mx9-h9xc)
- [github.com/marimo-team/marimo/pull/9098](https://github.com/marimo-team/marimo/pull/9098)
- [github.com/marimo-team/marimo/commit/c24d4806398f30be6b12ac…](https://github.com/marimo-team/marimo/commit/c24d4806398f30be6b12acd6c60d1d7c68cfd12a)

## Timeline

1. ID reserved Apr 8, 2026
2. Record published Apr 9, 2026
3. Added to CISA KEV Apr 23, 2026
4. Record last updated Apr 24, 2026

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## About CubePath

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Data from the CVE Program (MITRE), CISA KEV and FIRST EPSS. CVSS is owned by FIRST and used by permission. Not affiliated with or endorsed by MITRE, CISA or FIRST. Data as of Nov 10, 2026, 20:04 UTC. [Sources and licenses](https://cubepath.com/security/cve/legal)