Reference page — cumulative record through Sunday, October 4, 2026 UTC. Reference pages update as the archive grows; only dated daily editions are immutable pages of record.

CVE-2026-39987

CVE-2026-39987CRITICAL

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

  AV  AC  AT  PR  UI  VC  VI  VA   CVSS    EPSS   %ile   KEV
   N   L   N   N   N   H   H   H    9.3   .3786   98.5   YES

AFFECTED
  Product  Versions    Fixed
  marimo   < 0.23.0 –  —

TIMELINE
  Apr 8   Reserved by GitHub_M
  Apr 9   Published (CNA: GitHub_M)
  Apr 23  Added to CISA KEV, remediation due 2026-05-07

CWE-306 · CNA: GitHub_M · CVSS v4.0 · 5 references · KEV due May 7, 2026

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.

Lifecycle

Complete event history — 3 events, chronological
Date	Event	Detail
April 8, 2026	Reserved	Reserved by GitHub_M
April 9, 2026	Published	Published (CNA: GitHub_M)
April 23, 2026	KEV ADDED	Added to CISA KEV, remediation due 2026-05-07

Affected

Affected products and packages — 1 row
Vendor	Product / Package	Ecosystem	Version introduced	Fixed
marimo-team	marimo	—	< 0.23.0	—

Weaknesses

CWE-306

References (5)

https://github.com/marimo-team/marimo/commit/c24d4806398f30be6b12acd6c60d1d7c68cfd12a [x_refsource_MISC]
https://github.com/marimo-team/marimo/pull/9098 [x_refsource_MISC]
https://github.com/marimo-team/marimo/security/advisories/GHSA-2679-6mx9-h9xc [x_refsource_CONFIRM]
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-39987 [government-resource]
https://www.sysdig.com/blog/marimo-oss-python-notebook-rce-from-disclosure-to-exploitation-in-under-10-hours [third-party-advisory]

Authoritative record: CVE-2026-39987 at cve.org

Vendors: marimo-team

Weaknesses: CWE-306

About this page

This is a reference page, not a dated page of record. It assembles the complete lifecycle of CVE-2026-39987 from the CVE Program record, NVD enrichment, the CISA KEV catalog, EPSS, and OSV advisories. The box score's numbers (CVSS, EPSS, KEV status) are current as of Sunday, October 4, 2026 UTC and are re-derived as the archive grows; only dated daily editions are immutable pages of record. The authoritative source for this identifier is cve.org.