HarnessRouter is a self-hosted unified API for agent harnesses. From version 0.4.2 until 0.31.7, routes that accept a session ID or response ID validate only the caller's organization and do not enforce the workspace scope of a non-default workspace API key. A key holder who learns a non-guessable identifier from another workspace in the same organization can read sessions, conversation turns, files, traces, and responses, overwrite files, cancel or delete sessions, and publish share links. The issue does not cross organization boundaries, and console users, organization keys, and Default Workspace keys intentionally retain organization-wide access. This issue is fixed in version 0.31.7.