Marimo RCE Flaw CVE-2026-39987 Exploited Within 10 Hours of Disclosure
Summary: A pre-authenticated remote code execution flaw in Marimo, an open-source Python notebook, was exploited within 9 hours and 41 minutes of public disclosure, with the attacker building a working exploit from the advisory text alone and no proof-of-concept code available. CVE-2026-39987 (CVSS 9.3) affects all Marimo versions up to and including 0.20.4 because the /terminal/ws WebSocket endpoint skips authentication, and Sysdig later recorded 662 exploit events from 11 IP addresses across 10 countries between April 11 and 14, 2026, including deployment of an NKAbuse variant called "kagent" via a Hugging Face-hosted script.
What's compelling: The attacker needed no credentials and no published exploit - just the advisory description - and was harvesting .env files and SSH keys within minutes, which means the window between disclosure and compromise is now measured in hours, not days. CISA's April 23 KEV addition gives federal agencies until May 7, 2026, but the 662 recorded exploit events show that internet-facing developer tooling is being scanned and hit regardless of how widely it is deployed.
Read the original at The Hacker News ↗
- Topics
- Vulnerabilities & Patching
- Mentions
- CVE-2026-39987
- Related
- CVE-2026-39987: Marimo Remote Code Execution Vulnerability Known Exploited Vulnerabilities · Apr 23, 2026