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Fencer Vulns
critical 9.8

CVE-2026-39987 kev in the critical feed json

marimo Affected by Pre-Auth Remote Code Execution via Terminal WebSocket Authentication Bypass

published 2026-04-08 7 mo ago modified 2026-07-01 4 mo ago also GHSA-2679-6mx9-h9xc , PYSEC-2026-407 , EUVD-2026-20980

cvss
9.8
version 3.1, NVD
cisa kev
Exploited
added 2026-04-23
epss
99.7%
EPSS 99.7% chance of exploitation in 30 days, percentile 99.9%
public exploits
1
Exploit-DB, plus a Nuclei check

Summary

marimo is a reactive Python notebook. Prior to 0.23.0, Marimo has a Pre-Auth RCE vulnerability. The terminal WebSocket endpoint /terminal/ws lacks authentication validation, allowing an unauthenticated attacker to obtain a full PTY shell and execute arbitrary system commands. Unlike other WebSocket endpoints (e.g., /ws) that correctly call validate_auth() for authentication, the /terminal/ws endpoint only checks the running mode and platform support before accepting connections, completely skipping authentication verification. This vulnerability is fixed in 0.23.0.

Patch / fix

cisa required action Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.

  • pypi marimo 0.23.0
  • coreweave marimo 0.23.0

Timeline

  1. Published
  2. CISA SSVC: exploitation active
  3. Added to CISA KEV
  4. CISA patch deadline
  5. First public exploit (EDB-52673)

Known exploited

Added
6 mo ago
Patch by
2026-05-07 (6 mo ago)
Ransomware
Not known
Required action
Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
Vendor, product
Marimo, Marimo
CISA name
Marimo Remote Code Execution Vulnerability

CISA SSVC

Exploitation
Active, exploited in the wild
Automatable
yes
Technical impact
total
Assessed
6 mo ago

Exploit prediction

99.74% chance of exploitation in the next 30 days, higher than 99.9% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • EDB-52673 Marimo 0.20.4 - RCE webapps, 2026-09-02
  • Nuclei template Marimo <= 0.20.4 - Pre-Auth Terminal WebSocket RCE nuclei detection template
  • github.com https://github.com/marimo-team/marimo/security/advisories/GHSA-2679-6mx9-h9xc referenced PoC, tagged "exploit" by a source, unverified
  • sysdig.com https://www.sysdig.com/blog/marimo-oss-python-notebook-rce-from-disclosure-to-exploitation-in-under-10-hours referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 4.0 9.3 CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
CNA 4.0 9.3 CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
NVD 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
GitHub 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
OSV 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected packages

ecosystem package affected fixed in
pypi marimo
<0.23.0
0.23.0

Affected products

  • marimo-team marimo

Classification

Weakness
  • CWE-306 Missing Authentication for Critical Functionality

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.