CVE-2026-39987: marimo · Missing Authentication
Affects marimoSource CVE Database V5
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
- 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: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 30 Oct 2026.
What to do
Upgrade marimo to 0.23.0.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| marimo-teammarimo | Affected
| Fixed in
|
PyPImarimopkg:pypi/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 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
- github.com/marimo-team/marimo/security/advisories/GHSA-2679-6mx9-h9xc (opens in a new tab)
- github.com/marimo-team/marimo/pull/9098 (opens in a new tab)
- github.com/marimo-team/marimo/commit/c24d4806398f30be6b12acd6c60d1d7c68cfd12a (opens in a new tab)
- sysdig.com/blog/marimo-oss-python-notebook-rce-from-disclosure-to-exploitation-in-under-10-hours (opens in a new tab)
- cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-39987 (opens in a new tab)