The vulnerability in nesquena hermes-webui arises from improper limitation of pathname inputs (CWE-22) allowing authenticated attackers to set or change session workspace directories arbitrarily via API endpoints such as /api/session/new, /api/session/update, /api/chat/start, and /api/workspaces/add. This enables attackers to escape the intended workspace root and access or modify files outside the trusted directory scope, constrained only by the hermes-webui process permissions. The issue is present in version 0 of the product. The CVSS 4.0 vector indicates network attack vector, low attack complexity, no privileges required beyond authentication, no user interaction, and low to low impact on confidentiality, integrity, and availability.

An authenticated attacker can leverage this vulnerability to access or modify files outside the intended workspace directory, potentially leading to unauthorized data exposure or alteration within the permissions of the hermes-webui process. This could compromise the confidentiality and integrity of files accessible to the application. There is no indication of impact on availability or system-level privilege escalation from the provided data.

Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until an official fix is available, restrict access to authenticated users carefully and monitor for suspicious activity related to workspace path manipulation. Avoid exposing the affected API endpoints to untrusted networks or users. Do not assume the vulnerability is mitigated without vendor confirmation.