Summary
marimo vulnerable to proxy abuse of /mpl/{port}/
The /mpl/<port>/<route> endpoint, which is accessible without authentication on default Marimo installations allows for external attackers to reach internal services and arbitrary ports.
Details
From our understanding, this route is used internally to provide access to interactive matplotlib visualizations.
marimo/marimo/_server/main.py at main · marimo-team/marimo
This endpoint functions as an unauthenticated proxy, allowing an attacker to connect to any service running on the local machine via the specified <port> and <route>.
The existence of this proxy is visible in the application's code (marimo/_server/main.py), but there's no official documentation or warning about its behavior or potential risks.
Impact
CWE-441: Proxying Without Authentication
This vulnerability, as it can be used to bypass firewalls and access internal services that are intended to be local-only. The level of impact depends entirely on what services are running and accessible on the local machine.
Full Local Access: An attacker can use this proxy to connect to local services that answer to web sockets, HTTP or ASGI protocol, effectively gaining a foothold on the machine. Depending on the service, this can lead to remote code execution, data exfiltration, or further network penetration.
Exposure of Sensitive Services: Our scans of public-facing Marimo servers have shown that many are exposing sensitive internal services, including:
Old CUPS Servers: Could allow an attacker to view print jobs or configuration or depending on old vulnerabilities, allow RCE.
phpMyAdmin: Provides a web interface to a MySQL database, potentially exposing sensitive data.
RPCMapper: Can be used for network reconnaissance and enumerating services.
While you’d hope people wouldn’t expose marimo instances to the internet, we found numerous public Marimo instances using tools like Shodan. Many of these servers, some even hosted on cloud platforms like AWS GovCloud, were found to be vulnerable. This means the vulnerability isn't limited to a few isolated cases but is a widespread issue affecting production environments.
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Notes, this was discovered by devgi. I (acepace) followed up and also created this report.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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Frequently Asked Questions
- What is GHSA-XJV7-6W92-42R7? GHSA-XJV7-6W92-42R7 is a medium-severity security vulnerability in marimo (pip), affecting versions >= 0.9.20, < 0.16.4. It is fixed in 0.16.4.
- Which versions of marimo are affected by GHSA-XJV7-6W92-42R7? marimo (pip) versions >= 0.9.20, < 0.16.4 is affected.
- Is there a fix for GHSA-XJV7-6W92-42R7? Yes. GHSA-XJV7-6W92-42R7 is fixed in 0.16.4. Upgrade to this version or later.
- Is GHSA-XJV7-6W92-42R7 exploitable, and should I be worried? Whether GHSA-XJV7-6W92-42R7 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether GHSA-XJV7-6W92-42R7 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix GHSA-XJV7-6W92-42R7? Upgrade
marimoto 0.16.4 or later.