CVE-2026-39987

Published Apr 9, 2026

Last updated 2 months ago

Tunneling protocol

Overview

AI description

Automated description summarized from trusted sources.

CVE-2026-39987 identifies a pre-authentication remote code execution (RCE) vulnerability found in Marimo, a reactive Python notebook framework. The flaw stems from a lack of authentication validation on the `/terminal/ws` WebSocket endpoint. This oversight allows an unauthenticated attacker to gain access to a full PTY shell and execute arbitrary system commands. This vulnerability affects Marimo versions prior to 0.23.0. The issue has been actively exploited in the wild, with observed exploitation attempts occurring within hours of its public disclosure.

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.
Source: security-advisories@github.com
NVD status: Analyzed
Products: marimo

Risk scores

CVSS 4.0

Type: Secondary
Base score: 9.3
Impact score: -
Exploitability score: -
Vector string: 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
Severity: CRITICAL

CVSS 3.1

Type: Primary
Base score: 9.8
Impact score: 5.9
Exploitability score: 3.9
Vector string: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Severity: CRITICAL

Known exploits

Data from CISA

Vulnerability name: Marimo Remote Code Execution Vulnerability
Exploit added on: Apr 23, 2026
Exploit action due: May 7, 2026
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.

Weaknesses

security-advisories@github.com: CWE-306

Hype score: Not currently trending

Configurations

[
  {
    "nodes": [
      {
        "cpeMatch": [
          {
            "criteria": "cpe:2.3:a:coreweave:marimo:*:*:*:*:*:python:*:*",
            "matchCriteriaId": "EFA40E82-022F-42C3-A141-F4493A2A3E57",
            "versionEndExcluding": "0.23.0",
            "vulnerable": true
          }
        ],
        "negate": false,
        "operator": "OR"
      }
    ]
  }
]

References

Sources include official advisories and independent security research.