XSS in Marimo-Team Marimo
CVE-2026-54386
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.
Vulnerability class: XSS (Cross-Site Scripting)
Published · last modified .
CVSS v3 metric
CVSS v3 base score 6.1 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N.
EPSS exploit prediction
EPSS: 0.002 (15.1th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 15th percentile — 15.1% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.004 · newest: 0.002 · change: -0.002
Affected products
- Marimo-Team Marimo — versions 0
Weakness classification (CWE)
References
- github.com/marimo-team/marimo/releases/tag/0.23.9 (release-notes)
- github.com/marimo-team/marimo/pull/9789 (issue-tracking)
- github.com/marimo-team/marimo/commit/fdd55c8cf6260ae23bb411dc9d9269def5cf75d6 (patch)
- www.vulncheck.com/advisories/marimo-xss-via-file-query-parameter-in-assets-py (third-party-advisory)
Frequently asked questions
- What is CVE-2026-54386?
- CVE-2026-54386 is a medium-severity vulnerability in Marimo-Team Marimo, classified under Cross-site Scripting. CVSS score: 6.1/10. Published 2026-06-17.
- How severe is CVE-2026-54386?
- Medium severity. CVSS v3 base score is 6.1 out of 10.