# CVE-2026-54386: marimo XSS via file query parameter in notebook page

Source: https://junglewise.ai/threats/cve-2026-54386-marimo-xss-via-file-query-parameter-in-notebook-page  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-06-17. Updated: 2026-06-20  
License: CC BY 4.0 with a link back

CVE-2026-54386 · Severity: medium · CVSS 6.1 · Published 2026-06-17

marimo is an interactive Python notebook used for data science and development. A security vulnerability in the notebook interface allows an attacker to trick a user into clicking a malicious link, which then executes unauthorized code in the user's browser. This could allow an attacker to steal sensitive information or perform actions on behalf of the user within the marimo application.

Technologies: [marimo (PyPI)](https://junglewise.ai/threats/technologies/pypi-marimo). Vendors: [PyPI](https://junglewise.ai/threats/vendors/pypi).

## Quick answers

**Is CVE-2026-54386 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-54386 being exploited in the wild.

**How severe is CVE-2026-54386?** Medium severity, with a CVSS score of 6.1, published 17 June 2026.

**Which products and versions are affected?** marimo (PyPI) ECOSYSTEM:introduced=0,fixed=0.23.9.

**Is there a fix for CVE-2026-54386?** Yes. marimo (PyPI): upgrade to 0.23.9 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-54386 attacked?** It is attacked over the network, in a network appliance.

**Am I affected by CVE-2026-54386?** Check whether you run marimo (PyPI) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- marimo (PyPI): upgrade to 0.23.9 or later

  ```sh
  pip install "marimo>=0.23.9"
  ```


## Technical details

A reflected cross-site scripting (XSS) vulnerability exists in marimo's notebook page due to improper escaping of single quotes in the 'file' query parameter. This parameter is reflected into an inline JavaScript string literal within the service worker injection logic in 'assets.py'. An unauthenticated attacker can craft a malicious URL using a payload starting with '__new__' to bypass internal 404 checks and execute arbitrary JavaScript in the context of the victim's marimo server origin. The execution occurs without Content-Security-Policy (CSP) restrictions. The issue is fixed in version 0.23.9 by properly escaping the user-controlled file_key.

## Affected products

- marimo-team marimo before 0.23.9

## Identifiers

- CVE-2026-54386
- GHSA-8m59-7xv8-735h
- PYSEC-2026-2619

## Timeline

- 2026-06-04: patched: Fix merged in pull request #9789 and released in version 0.23.9
- 2026-06-17: disclosed: Vulnerability published by VulnCheck and NVD

## References

- [https://github.com/marimo-team/marimo/commit/fdd55c8cf6260ae23bb411dc9d9269def5cf75d6](https://github.com/marimo-team/marimo/commit/fdd55c8cf6260ae23bb411dc9d9269def5cf75d6)
- [https://github.com/marimo-team/marimo/pull/9789](https://github.com/marimo-team/marimo/pull/9789)
- [https://github.com/marimo-team/marimo/releases/tag/0.23.9](https://github.com/marimo-team/marimo/releases/tag/0.23.9)
- [https://www.vulncheck.com/advisories/marimo-xss-via-file-query-parameter-in-assets-py](https://www.vulncheck.com/advisories/marimo-xss-via-file-query-parameter-in-assets-py)

## Related threats

- [Marimo: Pre-Auth Remote Code Execution via Terminal WebSocket Authentication Bypass](https://junglewise.ai/threats/cve-2026-39987-marimo-pre-auth-remote-code-execution-via-terminal-websocket)
- [marimo vulnerable to proxy abuse of /mpl/{port}/](https://junglewise.ai/threats/marimo-vulnerable-to-proxy-abuse-of-mpl-port-57847eda)