Is CVE-2026-39987 actively exploited?

CVE-2026-39987 has no public evidence of in-the-wild exploitation as of 2026-04-23.

What is the CVSS score for CVE-2026-39987?

CVE-2026-39987 has a CVSS score of 9.3 (CRITICAL severity). 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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X.

How do I patch CVE-2026-39987?

Patch guidance is available from coreweave security advisories. CVEDatabase generates AI-assisted remediation guidance on demand for CVE-2026-39987.

Fix CVE-2026-39987 - CRITICAL coreweave marimo

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.

CVSS Metrics

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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Attack Vector: network
Complexity: low
Privileges: none
User Action: none
Confidentiality: undefined
Integrity: undefined
Availability: undefined
Weaknesses: CWE-306 · Missing Authentication

Metadata

Primary Vendor: COREWEAVE
Published: 4/9/2026
Last Modified: 4/23/2026
Source: NIST NVD
Note: Verify all details with official vendor sources before applying patches.

CVE-2026-39987

Description

CVSS Metrics

Metadata

Affected Products

Remediation Guidance

Executive Summary