Marimo 0.20.4 · RCE
Affects MarimoSource Exploit-DB RSS Feed
Exploited in the wild · KEV due 7 May 2026 · public exploit available (Exploit-DB) · 99% EPSS : apply the vendor's fix or mitigations to Marimo now.
Data as of 5 Nov 2026, 00:01 UTC
- KEV deadline
- US federal agencies must patch by this date; a sensible deadline for everyone else. Other KEV due dates
- EPSS
- 99.7% chance of exploitation in 30 days – higher than 99% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:NExploitation evidence
t = 0 is the CVE’s publication on cve.org
Disclosed: evidence found.
CVE published 9 Apr 2026
Detectable: evidence found.
nuclei template: Marimo <= 0.20.4 - Pre-Auth Terminal WebSocket RCE
Weaponized: evidence found.
Exploited in the wildExploited: evidence found.
Listed in CISA KEV 14 days after disclosure
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
Timeline
CVE ID reserved
by GitHub, Inc.
, 41 hours before disclosure
CVE published
on cve.org
, t = 0
In Threat Radar
record ingested
, 34 minutes after disclosure
Added to CISA KEV (opens in a new tab)
exploitation confirmed
, 14 days after disclosure
KEV remediation due
US federal deadline
, 28 days after disclosure
First Exploit-DB entry (opens in a new tab)
Marimo 0.20.4 - RCE
, 146 days after disclosure
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), CISA KEV (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 5 Nov 2026.
What to do
Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
npmmarimopkg:npm/marimoOther threats | Affected
| Fixed in– |
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
Description
Marimo version 0.20.4 is associated with a remote code execution (RCE) vulnerability identified as CVE-2026-39987. The available information is limited, with no detailed technical data or patch information provided.
Indicators of compromise
Exploit source code
Title: Marimo 0.20.4 - RCE
Date: August 2nd, 2026
Exploit Author: Jason Bernier
Vendor Homepage: https://marimo.io/
Software Link: https://github.com/marimo-team/marimo
Version: <=0.20.4
Tested on: Ubuntu 24.04
CVE: CVE-2026-39987
Advisory:
https://github.com/marimo-team/marimo/security/advisories/GHSA-2679-6mx9-h9xc
"""
Exploit script for CVE-2026-39987, a pre-authentication Remote Code Execution (RCE) vulnerability in Marimo.
The exploit leverages a WebSocket endpoint to execute arbitrary c…