A critical pre-authentication remote code execution vulnerability in Marimo allows unauthenticated attackers to execute arbitrary system commands, and it is currently being exploited in the wild.

The /terminal/ws WebSocket endpoint fails to perform authentication validation. This allows an unauthenticated attacker to establish a connection, obtain a full PTY shell, and execute arbitrary system commands on the underlying host.

The CVSS score of 9.5 reflects the extreme risk posed by this vulnerability. Since the flaw is reachable without authentication, it allows for trivial remote code execution, which can lead to complete server takeover, lateral movement within the network, and the deployment of malicious payloads like the NKAbuse malware. The high exploitability and rapid weaponization by attackers make this a top-tier security priority.

Immediate Action: Update the Marimo package to version 0.23.0 or later immediately.

Proactive Monitoring: Audit logs for suspicious connections to the /terminal/ws endpoint and monitor for anomalous child processes spawned by the Marimo service.

Compensating Controls: Use a Web Application Firewall (WAF) to block unauthorized WebSocket traffic to the /terminal/ws endpoint until the patch can be applied.

Public Exploit Available: Yes (multiple public GitHub PoCs exist)

Due to the ease of exploitation and the confirmed active use in the wild, this vulnerability presents an immediate and critical risk. All systems running vulnerable versions of Marimo must be updated to version 0.23.0 or taken offline until the update can be verified.