Critical severity · published Apr 9, 2026
CVE-2026-39987
marimo Affected by Pre-Auth Remote Code Execution via Terminal WebSocket Authentication Bypass
In wildKEV
9.8
CVSS
99.6%
EPSS
Yes
On KEV
Description
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
High
Integrity
High
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)99.6% · higher than 100% of CVEs
Exploited in the wildYes
CISA KEVListed Apr 23, 2026
Federal remediation dueMay 7, 2026
Ransomware campaign useNot known
Affected products
Which versions
MA
marimo · marimo-team
< 0.23.0 · source: vendor, NVD, KEV
In the news
VulnerabilityHigh
Attackers Use LLM Agent for Post-Exploitation After Marimo CVE-2026-39987 Exploit
An unknown threat actor has been observed using a large language model (LLM) agent to conduct post-compromise actions after obtaining initial access following the exploitation of a publicly-accessible Marimo network using a recently disclosed vulnerability.
"The attacker compromised an internet-reachable Marimo notebook via CVE-2026-39987, extracted two cloud credentials from the compromised
May 29, 2026·The Hacker News
VulnerabilityCritical
[CISA KEV] CVE-2026-39987: Marimo Marimo - Marimo Remote Code Execution Vulnerability
Marimo contains an pre-authorization remote code execution vulnerability, allowing an unauthenticated attacked to shell access and execute arbitrary system commands.
MAMarimoCVE-2026-39987
Apr 23, 2026·CISA KEV
VulnerabilityCritical
CVE-2026-39987: Marimo RCE exploited in hours after disclosure
A critical flaw, tracked as CVE-2026-39987, in the open-source Python notebook tool Marimo was exploited within 10 hours of disclosure. A critical flaw in Marimo, tracked as CVE-2026-39987 (CVSS score of 9.3) was exploited just 10 hours after disclosure (On April 8, 2026). Sysdig Threat Research Team observed exploitation of the Marimo flaw within 9 […]
Apr 11, 2026·Security Affairs
VulnerabilityCritical
Marimo RCE Flaw CVE-2026-39987 Exploited Within 10 Hours of Disclosure
A critical security vulnerability in Marimo, an open-source Python notebook for data science and analysis, has been exploited within 10 hours of public disclosure, according to findings from Sysdig.
The vulnerability in question is CVE-2026-39987 (CVSS score: 9.3), a pre-authenticated remote code execution vulnerability impacting all versions of Marimo prior to and including
Apr 10, 2026·The Hacker News
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-39987
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-39987
CISA KEV catalogue
https://www.cisa.gov/known-exploited-vulnerabilities-catalog
Patch
https://github.com/marimo-team/marimo/commit/c24d4806398f30be6b12acd6c60d1d7c68cfd12a
Issue Tracking
https://github.com/marimo-team/marimo/pull/9098
Exploit
https://github.com/marimo-team/marimo/security/advisories/GHSA-2679-6mx9-h9xc
US Government Resource
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-39987
Exploit
https://www.sysdig.com/blog/marimo-oss-python-notebook-rce-from-disclosure-to-exploitation-in-under-10-hours
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