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CVE-2026-39987

9.8, critical Known exploited

Marimo Remote Code Execution Vulnerability

NVD (opens in a new tab) CVE.org (opens in a new tab) CISA KEV catalogue (opens in a new tab)
CVSS
9.8, critical critical CVSS v3.1
EPSS, next 30 days
38% higher than 98.5% of scored CVEs
Exploitation
Confirmed in the wild
Published
9 Apr 20266 months ago

Known exploited

CISA added this to the Known Exploited Vulnerabilities Catalog on 23 Apr 2026. US federal agencies had to remediate by 7 May 2026, a deadline that has passed.

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.

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.

Details

Vendor
Marimo
Product
marimo
Weakness
CWE-306 (opens in a new tab)
Status
Analyzed
Updated
17 Jun 2026
Assigner
security-advisories@github.com

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

References 5

Exploit code 2

Patches and fixes 2

Other references 1

The kind is read from NVD's tags where present and from the shape of the URL otherwise, so treat it as a hint.

Beyond this page

Is CVE-2026-39987 in your network?

This page tells you how dangerous CVE-2026-39987 is out there. Whether it sits on one of your devices, only a scan of your own network can tell. That is what our systems do, every day, for the companies we protect.

CVE-2026-39987 is in the CISA catalogue of exploited vulnerabilities: attackers are already exploiting it.

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  • EXYS7950 KONDRA

    Detect it if it's exploited

    Until the patch is applied, Kondra monitors your network, events and endpoints in real time. It keeps an inventory of the software installed on every endpoint, and its anomaly detection rules flag what an attacker does once inside.

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Check your exposure

Assembled from the NVD 2.0 API, the CISA Known Exploited Vulnerabilities Catalog and FIRST EPSS. Scores are as of our last collection on 17 Oct 2026, not the live upstream state.