CVE-2026-54386Network attack vector

Reflected XSS via unsafe inline script interpolation

Published Jun 17, 2026 · Updated Jun 17, 2026

Reflected XSS in marimo before 0.23.9 allows remote attackers to execute JavaScript in a victim's server origin via a crafted notebook URL. The _inject_service_worker() path in assets.py embeds the user-controlled file_key in a single-quoted inline JavaScript string without safe JSON encoding. A victim must open the crafted link; a new-prefixed value bypasses the 404 check, allowing script execution without CSP restrictions.

CVSS severity5.1
Medium
EPSS probability0.24%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Reflected XSS in marimo before 0.23.9 allows remote attackers to execute JavaScript in a victim's server origin via a crafted notebook URL. The _inject_service_worker() path in assets.py embeds the user-controlled file_key in a single-quoted inline JavaScript string without safe JSON encoding. A victim must open the crafted link; a new-prefixed value bypasses the 404 check, allowing script execution without CSP restrictions.

The record

CVE
CVE-2026-54386
Published
Jun 17, 2026
Updated
Jun 17, 2026
Vendor
Marimo Inc.
Product
marimo
Classifications
CWE-79, T1189
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 17, 2026CVE publishedPublication date reported by the CVE source.
  2. Jun 17, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <0.23.9

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Marimo Inc. · marimoversion=0 <0.23.9

Published CVSS scores

5.1GitHub Advisory DatabaseCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1189Drive-by Compromise

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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