The vulnerability is a trust‑boundary failure that permits a logged‑in user to set a session workspace to any existing directory on the host by altering path parameters in API endpoints such as /api/session/new, /api/session/update, /api/chat/start, and /api/workspaces/add. This flaw allows the attacker to read from or write to files outside the intended workspace boundary using the hermes-webui process’s filesystem privileges.

The affected product is nesquena’s hermes-webui application. No specific version numbers are listed in the advisory; the issue was addressed in later releases, such as tag v0.50.34. All deployments of the web interface that remain on earlier versions are potentially vulnerable.

The CVSS score is 5.3, indicating moderate severity. EPSS data is not available, and the issue is not currently listed in the CISA KEV catalog. The flaw requires the attacker to be authenticated and to target API requests that accept a workspace path parameter. Successful exploitation grants the attacker arbitrary file system access within the hermes‑webui process’s privileges, which may lead to data disclosure, tampering, or execution of malicious code if the process has write access to executable files.