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critical·Product Based Web Vulnerabilities·Updated Apr 9, 2026

CVE-2026-39987 Scanner

CVE-2026-39987 Scanner - Remote Code Execution (RCE) vulnerability in Marimo

Est. Time~10 seconds
Scan TypeSingle Scan
Targetsdomain, subdomain, ipv4
CostFree
2.8k
Times Used
continuous scan runs
6.1k
Continuously Checked
assets under CS
0
Vulnerabilities Found
confirmed findings
References
🔴
CISA Known Exploited Vulnerability
This CVE is actively exploited in the wild. CISA mandates federal agencies to patch immediately.
CVECVE-2026-39987
9.3
CVSScritical
Exploitable remotely over the internet · no authentication required.

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.

Attack Vector
Network
Privileges Req.
None
User Interaction
None
Affected
marimoby marimo-team
< 0.23.0
Updated Sep 10, 2026View on NVD →
Detail

The Marimo software is used by various organizations and developers for creating secure and scalable applications. It provides a comprehensive platform for building and deploying web-based solutions, offering flexibility and ease of use. Marimo is typically utilized in environments where quick deployment and efficient management are crucial. Its integration capabilities often make it a popular choice for businesses aiming to optimize their web services. Widely adopted in both small and large scale operations, Marimo supports a range of applications across different sectors. Its design and functionality focus on delivering robust performance with customizable features for developers.

The vulnerability in question allows for Remote Code Execution (RCE) within the Marimo application. An unauthenticated attacker can exploit this flaw by connecting to the exposed terminal WebSocket endpoint. This endpoint lacks proper authentication validation, which makes it susceptible to unauthorized access. Upon exploitation, attackers may execute arbitrary OS commands on the affected server. This high-severity vulnerability compromises the integrity and security of the server environment. The exploitation does not require user interaction, making it particularly dangerous for unattended systems.

The vulnerable endpoint in Marimo is /terminal/ws. This WebSocket endpoint lacks proper authentication checks, allowing unauthenticated access. Attackers can establish a connection using WebSocket protocol to gain a PTY shell. This access enables them to execute system-level commands remotely. During exploitation, various system commands can be dispatched to the server, leading to unauthorized actions. The vulnerability arises due to the absence of robust security mechanisms over this endpoint. Ensuring that proper authentication validation is applied is key to mitigating this issue.

If left unpatched, the RCE vulnerability can lead to severe security breaches. Attackers can gain full control over the affected system and manipulate its operations. Potential impacts include data theft, system interruption, and unauthorized access to sensitive information. The vulnerability enables attackers to run malicious scripts and commands, potentially causing system-wide damages. This compromise could also allow attackers to establish a foothold within a network, leading to further exploitation. Such vulnerabilities, if exploited, can severely damage reputation and result in significant financial and operational losses.

REFERENCES

Solution Advice
  • Upgrade to Marimo version 0.23.0 or later to ensure authentication validation at the terminal WebSocket endpoint.
  • Regularly audit and review access controls for WebSocket endpoints within web applications.
  • Implement network-level security measures to restrict unauthorized access to sensitive endpoints.
  • Enable logging and monitoring to detect any unauthorized access attempts or unusual activities.
  • Educate teams on the importance of maintaining software versions and applying security patches promptly.

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CVE-2026-39987 Scanner - Remote Code Execution (RCE) vulnerability in Marimo | S4E