marimo-team marimo up to 0.22.x WebSocket Endpoint /terminal/ws validate_auth missing authentication

Summaryinfo

A vulnerability, which was classified as critical, was found in marimo-team marimo up to 0.22.x. This issue affects the function validate_auth of the file /terminal/ws of the component WebSocket Endpoint. Such manipulation leads to missing authentication. This vulnerability is traded as CVE-2026-39987. The attack may be launched remotely. Furthermore, there is an exploit available. You should upgrade the affected component.

Detailsinfo

A vulnerability was found in marimo-team marimo up to 0.22.x. It has been rated as critical. Affected by this issue is the function validate_auth of the file /terminal/ws of the component WebSocket Endpoint. The manipulation with an unknown input leads to a missing authentication vulnerability. Using CWE to declare the problem leads to CWE-306. The product does not perform any authentication for functionality that requires a provable user identity or consumes a significant amount of resources. Impacted is confidentiality, integrity, and availability. CVE summarizes:

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.

The advisory is shared for download at github.com. This vulnerability is handled as CVE-2026-39987 since 04/08/2026. The exploitation is known to be easy. The attack may be launched remotely. No form of authentication is required for exploitation. Technical details as well as a exploit are known.

It is declared as attacked. This issue was added on 04/23/2026 to the CISA Known Exploited Vulnerabilities Catalog with a due date of 05/07/2026:

Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.

Upgrading to version 0.23.0 eliminates this vulnerability.

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Productinfo

Vendor

• marimo-team

Name

• marimo

Version

• 0.1
• 0.2
• 0.3
• 0.4
• 0.5
• 0.6
• 0.7
• 0.8
• 0.9
• 0.10
• 0.11
• 0.12
• 0.13
• 0.14
• 0.15
• 0.16
• 0.17
• 0.18
• 0.19
• 0.20
• 0.21
• 0.22

Website

• Product: https://github.com/marimo-team/marimo/

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