The Archon project contains a missing authentication flaw in its control API endpoints (/api/*). Because the API binds to all interfaces (0.0.0.0) by default, any host that can reach the application can send requests without credentials. The API exposes an AI coding agent that runs with bypassPermissions, allowing the attacker to send messages that result in arbitrary command execution on the host as the Archon user. This leads to full remote code execution, data exfiltration, and potential system compromise.

The vulnerability impacts all Archon releases from 0.2.13 through 0.11.1. Users running any of these versions on accessible networks are at risk. All instances of the /api/* control API that have not been patched or reconfigured are vulnerable.

The base CVSS score of 9.3 indicates high severity. The EPSS score is very low (<1%), indicating a low probability of exploitation in the wild, and the issue is not yet listed in the CISA KEV catalog, but the lack of authentication combined with a network-facing endpoint means that any network attacker can exploit the flaw. Successful exploitation gives the attacker the same privileges as the Archon service user, enabling complete control over the host. Given the simplicity of the attack, the risk is high and immediate action is recommended.