What happened
Before 0.8.0, Helio's dashboard sideband validated CORS permission by checking whether the request Hostname started with a private-network (10./172.16-172.31./192.168.) prefix rather than confirming a trusted origin, allowing requests from a crafted host to reach the agent dashboard.
Why it matters
An MCP proxy dashboard is a management surface for AI agent tooling; a CORS bypass lets a malicious page perform actions or read state against the agent's control plane.
Attack vector
The dashboard sideband validated CORS request origins by matching the hostname against a private-network string prefix rather than validating the source as a trusted/local origin, so a cross-origin attacker-originated request could pass the origin check.
Affected systems
gethelio/helio < 0.8.0 (dashboard sideband CORS)
Mitigation
Upgrade to helio 0.8.0; bind the dashboard to loopback and restrict CORS to the expected local origin.