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VulnerabilityPublished Updated

CVE-2026-39987: marimo · Missing Authentication

Affects marimoSource CVE Database V5

0
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Exploited in the wild · KEV due 7 May 2026 · public exploit available (Exploit-DB) · 99% EPSS : upgrade to 0.23.0 now.

Data as of 30 Oct 2026, 11:52 UTC

CVSS 4.0 base score
9.3Critical
How severe the flaw is on the 0–10 CVSS scale.
KEV deadline
 US federal agencies must patch by this date; a sensible deadline for everyone else. Other KEV due dates
EPSS
99.5% chance of exploitation in 30 days – higher than 99% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 0.23.0
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

Exploitation evidence

t = 0 is the CVE’s publication on cve.org

  1. Disclosed: evidence found.

    CVE published 9 Apr 2026

  2. Exploited in the wild: evidence found.

    Listed in CISA KEV 14 days after disclosure

  3. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

Timeline

  1. CVE ID reserved

    by GitHub, Inc.

    , 41 hours before disclosure

  2. CVE published

    on cve.org

    , t = 0

  3. In Threat Radar

    record ingested

    , 34 minutes after disclosure

  4. , 14 days after disclosure

  5. KEV remediation due

    US federal deadline

    , 28 days after disclosure

  6. , 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 30 Oct 2026.

What to do

Upgrade marimo to 0.23.0.

Affected software

ProductAffectedFixed in
marimo-teammarimoAffected
  • <0.23.0
Fixed in
  • 0.23.0
PyPImarimopkg:pypi/marimoOther threatsAffected
  • <0.23.0
Fixed in
  • 0.23.0

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

Description

Marimo versions prior to 0.23.0 contain a critical vulnerability where the /terminal/ws WebSocket endpoint lacks authentication. This allows unauthenticated attackers to gain a full PTY shell and execute arbitrary system commands remotely. The issue arises because this endpoint does not perform authentication validation unlike other endpoints. The vulnerability is fixed in version 0.23.0.

Reports on CVE-2026-39987

References

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