Marimo Python Notebook Pre-Auth RCE Weaponized 9 Hours After Disclosure as CISA Adds CVE to KEV Catalog
An unauthenticated WebSocket flaw in the popular Marimo notebook (CVE-2026-39987, CVSS 9.3) was weaponized within 9 hours 41 minutes of disclosure, with credential theft completed in under three minutes. CISA has since added the bug to its KEV catalog with a May 7 federal deadline.