Attackers Use LLM Agent for Post-Exploitation After Marimo CVE-2026-39987 Exploit

Attackers exploited CVE-2026-39987 in Marimo and used an LLM agent to conduct post-exploitation activities including credential extraction, AWS access, and database exfiltration.

• •CVE-2026-39987 is a pre-authenticated RCE vulnerability in Marimo versions before 0.23.0 allowing unauthenticated arbitrary command execution
• •The attack chain extracted credentials, retrieved SSH keys from AWS Secrets Manager, and exfiltrated an internal PostgreSQL database via SSH sessions
• •Sysdig identified four LLM agent indicators: improvised database operations without prior schema knowledge, Chinese-language planning comments, machine-optimized commands with delimiters, and chained value handoffs
• •LLM agents adapt to unexpected situations in real-time, unlike scripted attackers that abort or fall back to hardcoded procedures