CVE-2026-54386 marimo < 0.23.9 XSS via file Query Parameter in assets.py
Unauthenticated attackers can inject arbitrary JavaScript via a crafted link, enabling code execution in the victim's browser context.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2026-54386?
CVE-2026-54386 is a medium-severity cross-site scripting vulnerability in marimo-team marimo, published on 17 Jun 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Official description
marimo before 0.23.9 contains a reflected cross-site scripting vulnerability in the notebook page that allows unauthenticated attackers to inject arbitrary JavaScript by exploiting improper escaping of single quotes in the file query parameter reflected into an inline JavaScript string literal. Attackers can craft a malicious link with a payload beginning with __new__ to bypass the 404 check and inject JavaScript into the page, which executes without Content-Security-Policy restrictions in the origin of a victim's marimo server.
Weakness: CWE-79
Which versions are affected by CVE-2026-54386?
3 open source packages ship an affected version, including marimo.
| Package | Affected | Fixed in |
|---|---|---|
marimo PyPI | All versions | 0.23.9 |
marimo PyPI | All versions | 0.23.9 |
marimo PyPI | All versions | 0.23.9 |
How do I fix CVE-2026-54386?
Upgrade marimo to 0.23.9 or later.
Escape output for the context it lands in and set a strict Content Security Policy. Upgrading the affected component is the real fix. More about Cross-site scripting.
Is CVE-2026-54386 being exploited?
There is no known exploitation of CVE-2026-54386 in the wild and no public exploit code.
Sources
Also known as GHSA-8m59-7xv8-735h, PYSEC-2026-2619.