A flaw in Sim versions prior to 0.8.14 causes the application to treat tool requests that begin with the literal string "/api/" as internal. The vulnerability is inferred to allow Remote Code Execution because the validation path normally checks for external hostnames is bypassed, granting a short‑lived internal authentication token. An authenticated workflow author can therefore invoke internal endpoints such as POST /api/function/execute, resulting in remote server‑side code execution as the internal application user, compromising confidentiality, integrity, and availability.

The vulnerability applies to the Sim software produced by Sim Studio AI, specifically any deployment of the "sim" product with a version earlier than 0.8.14. The affected component lies in the Tool URL routing and authentication module that handles incoming requests for user‑supplied HTTP blocks.

The impact is inferred to be Remote Code Execution. The CVSS score of 5.3 indicates a moderate severity, but the lack of an EPSS score and absence from the CISA KEV catalog do not lessen the potential impact because the flaw grants internal execution rights. Attackers need an authenticated workflow author to supply a specially crafted path starting with "/api/"; if they can then reach internal‑only endpoints such as POST /api/function/execute, arbitrary code may be run. No public exploit has been observed, yet the straightforward bypass offers a viable attack surface for those with authoring privileges.