CVE-2026-39987

KEVMarimo Remote Code Execution Vulnerability

Description

Marimo contains an pre-authorization remote code execution vulnerability, allowing an unauthenticated attacked to shell access and execute arbitrary system commands.

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 4.0 vector

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

PublishedApr 9, 2026

Last modifiedJun 17, 2026

Added to KEVApr 23, 2026

Remediation dueMay 7, 2026

References

github.com/marimo-team/marimo/commit/c24d4806398f30be6b12acd6c60d1d7c68cfd12aPatch
github.com/marimo-team/marimo/pull/9098Issue TrackingPatch
github.com/marimo-team/marimo/security/advisories/GHSA-2679-6mx9-h9xcExploitMitigation
cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-39987US Government Resource
sysdig.com/blog/marimo-oss-python-notebook-rce-from-disclosure-to-exploitation-in-under-10-hoursExploitThird Party Advisory

0 recent articles mention this CVE

Risk assessment · Critical

Actively exploited. Patch immediately.

Exploitation: Confirmed in the wild (CISA KEV)
Federal remediation deadline: Overdue by 172 days
CVSS: 9.3 CRITICAL
EPSS (30-day exploit probability): 99.6% · top 1% of all CVEs
Weakness: CWE-306
Attack vector: Network, remotely reachable
Preconditions: No privileges and no user interaction

Recommended actions

1.Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
2.Treat as emergency change: patch or isolate internet-facing instances first.
3.Review exposure: confirm which instances are reachable from the internet and restrict access until patched.
4.Hunt for compromise: review logs for the disclosure window, not just from the patch date.

Assessment is derived automatically from the live signals above; verify against your own asset inventory.