CVE-2026-39987

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.

Overview

State: PUBLISHED
Assigner (CNA): GitHub_M
CVSS severity: CRITICAL
CVSS score: 9.3 / 10
CVSS vector: 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
Effective score: 9.3 / 10 CRITICAL source: CNA overview
CWE(s): CWE-306
Reserved: 2026-04-08
Published: 2026-04-09 17:16 UTC
Last updated: 2026-04-24 03:55 UTC
Source: https://raw.githubusercontent.com/CVEProject/cvelistV5/main/cves/2026/39xxx/CVE-2026-39987.json
Linked Threat: CVE-2026-39987 — Marimo Marimo: Marimo Remote Code Execution Vulnerability

CISA Known Exploited Vulnerabilities CISA KEV

CISA has confirmed in-the-wild exploitation of this CVE. Federal agencies must remediate by the due date below; private orgs should treat it as priority-1.

Vulnerability name: Marimo Remote Code Execution Vulnerability
Vendor / project: Marimo
Product: Marimo
Date added to KEV: 2026-04-23
Remediation due: 2026-05-07
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.
Ransomware campaign use: Unknown
CISA notes: https://github.com/marimo-team/marimo/security/advisories/GHSA-2679-6mx9-h9xc ; https://nvd.nist.gov/vuln/detail/CVE-2026-39987
CISA listing: www.cisa.gov/known-exploited-vulnerabilities-catalog

NVD triage scoring NVD CVE 2.0

Layer NVD adds on top of the CNA's CVE record — published / last-modified timestamps, exploitability / impact subscores, and the FIRST.org EPSS probability that this CVE will be exploited in the wild in the next 30 days.

NVD published: 2026-04-09 18:17:02 UTC
NVD last modified: 2026-04-23 20:15:29 UTC
NVD CVSS v3.1: 9.8 / 10 CRITICAL source: nvd@nist.gov
NVD CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Exploitability subscore: 3.9 / 10
Impact subscore: 5.9 / 10
EPSS score: 0.8217 (probability of exploitation in next 30 days)
EPSS percentile: 99.23% vs all CVEs — higher = more likely to be exploited, as of 2026-05-24

European Union Vulnerability Database ENISA EUVD

ENISA's official EU repository for curated vulnerability intelligence. Carries a separate identifier (EUVD-YYYY-NNNN) and frequently exposes an earlier-published description + CVSS than NVD does.

EUVD ID: EUVD-2026-20980
Assigner: GitHub_M
Published: Apr 9, 2026, 5:16:55 PM
Updated: Apr 24, 2026, 3:55:20 AM
EUVD base score (CVSS 4.0): 9.3 / 10
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
EUVD-reported EPSS: 82.1700
Vendors: marimo-team
Products: marimo (< 0.23.0)

ENISA 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.

EUVD references (3)

Affected products (1)

Vendor	Product	Versions	Platforms
marimo-team	marimo	`< 0.23.0` (affected)	—

Affected products — CPE 2.3 (1) NVD

NVD's normalized CPE 2.3 matchers, used by vendor tools (vulnerability scanners, asset managers) for automated detection. Compare with the CNA's free-text "Affected products" section above.

cpe:2.3:a:coreweave:marimo:*:*:*:*:*:python:*:*

Vendor references (3)

References embedded in the original CVE record by the assigning CNA.

https://github.com/marimo-team/marimo/security/advisories/GHSA-2679-6mx9-h9xc x_refsource_CONFIRM
https://github.com/marimo-team/marimo/pull/9098 x_refsource_MISC
https://github.com/marimo-team/marimo/commit/c24d4806398f30be6b12acd6c60d1d7c68cfd12a x_refsource_MISC

Web references (8)

DuckDuckGo results ranked by threat-intel / vendor advisory domains. Generated by the 🔎 Find references (web) button above — same flow as the Remediations search.

http://cwe.mitre.org/data/definitions/306.html rapid7:cwe.mitre.org
https://attackerkb.com/topics/CVE-2026-39987 rapid7:attackerkb.com
https://euvd.enisa.europa.eu/vulnerability/EUVD-2026-20980 rapid7:euvd.enisa.europa.eu
https://github.com/marimo-team/marimo/commit/c24d4806398f30be6b12acd6c60d1d7c68cfd12a rapid7:github.com
https://github.com/marimo-team/marimo/pull/9098 rapid7:github.com
https://github.com/marimo-team/marimo/security/advisories/GHSA-2679-6mx9-h9xc rapid7:github.com
https://nvd.nist.gov/vuln/detail/CVE-2026-39987 rapid7:nvd.nist.gov
https://www.cve.org/CVERecord?id=CVE-2026-39987 rapid7:www.cve.org

NVD-tagged references (5)

Reference list NVD curates from the CNA record, vendor advisories, and third-party reports. The tag chips below are NVD's analyst-assigned categories.

https://github.com/marimo-team/marimo/commit/c24d4806398f30be6b12acd6c60d1d7c68cfd12a security-advisories@github.com Patch
https://github.com/marimo-team/marimo/pull/9098 security-advisories@github.com Issue TrackingPatch
https://github.com/marimo-team/marimo/security/advisories/GHSA-2679-6mx9-h9xc security-advisories@github.com ExploitMitigationVendor Advisory
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-39987 134c704f-9b21-4f2e-91b3-4a467353bcc0 US Government Resource
https://www.sysdig.com/blog/marimo-oss-python-notebook-rce-from-disclosure-to-exploitation-in-under-10-hours 134c704f-9b21-4f2e-91b3-4a467353bcc0 ExploitThird Party Advisory

Indicators (2)

IOCs linked to the auto-promoted Threat row.

Type	Value	VirusTotal	Attached
cwe	`CWE-306`	no local data	2026-05-14 02:58 UTC
cve	`CVE-2026-39987`	no local data	2026-05-14 02:58 UTC

Remediations (9)

Remediations are stored against the linked Threat row; the list below is deduplicated across both pages.

CVE-2026-39987 - Security Alert | The Fastest Security Intelligence Feed

web:zerodaysignal.com

Real-time security alerts. No fluff. Prioritized by severity. Patch first, sleep later.

2026-05-14 07:48 UTC
Microsoft Patch Tuesday May 2026 - 120 Vulnerabilities Fixed, Including ...

web:cybersecuritynews.com

Microsoft's May 2026 Patch Tuesday lands with a heavy enterprise focus, fixing 120 vulnerabilities across Windows, Office, Azure, developer tools, and Microsoft 365 apps, including 29 remote code execution (RCE) flaws rated Critical.

2026-05-14 07:48 UTC
Nvd - Cve-2026-39987

web:nvd.nist.gov

An official website of the United States government Here's how you know

2026-05-14 07:48 UTC
Security Update Guide - Microsoft

web:portal.msrc.microsoft.com

The Security Update Guide provides information on the latest Microsoft security updates, helping users understand and address potential vulnerabilities effectively.

2026-05-14 07:48 UTC
KB5090407 - Description of the security update for SQL Server 2019 CU32 ...

web:support.microsoft.com

Summary Improvements and fixes included in this update How to obtain and install the update How to obtain or download the latest cumulative update package for Linux More information File information Information about protection and security Summary This security update contains fixes and resolves vulnerabilities. To learn more about the vulnerabilities, see the following security advisories ...

2026-05-14 07:48 UTC
Microsoft and Adobe Patch Tuesday, April 2026 Security Update Review

web:blog.qualys.com

With Qualys Policy Audit's out-of-the-box mitigation or Compensatory Controls, which reduce the risk of a vulnerability being exploited because the remediation ( fix / patch ) cannot be done immediately, these security controls are not recommended by any industry standards, such as CIS and DISA-STIG.

2026-05-14 07:48 UTC
Dangerous Fake Microsoft Windows Update Confirmed—Do Not Download

web:www.forbes.com

As security researchers warn about a dangerous Microsoft Windows update that isn't legitimate, users must pay close attention to what they are actually downloading.

2026-05-14 07:48 UTC
CVE-2026-39987 | Tenable®

web:www.tenable.com

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 ...

2026-05-14 07:48 UTC
CISA Required Action

CISA KEV

Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable. Due date: 2026-05-07 Known ransomware campaign use: Unknown

2026-05-14 01:13 UTC

AI Forensic Analysis

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Raw JSON

The full cvelistV5 record. Download as CVE-2026-39987.json.

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