An unauthenticated remote code execution vulnerability exists in Microsoft WinML CLI prior to version 0.4.0, posing a critical risk to user systems.

The application exposes an unauthenticated localhost HTTP API with permissive cross-origin policies, allowing a malicious website to trigger arbitrary code execution by forcing the tool to load untrusted model code. This flaw stems from a lack of authentication and improper validation of the trust_remote_code parameter.

Successful exploitation allows an attacker to execute arbitrary code with the privileges of the user running the WinML CLI service. Given the CVSS score of 8.6, this represents a high-severity risk that could lead to full system compromise, data theft, or the installation of persistent malware, potentially resulting in significant operational and reputational damage.

Immediate Action: Update Microsoft WinML CLI to version 0.4.0 or later immediately to resolve the authentication and cross-origin configuration flaws.

Proactive Monitoring: Review browser logs and network traffic for suspicious cross-origin requests originating from untrusted domains directed toward localhost ports.

Compensating Controls: If immediate patching is not possible, ensure that users do not navigate to untrusted websites while the WinML CLI service is active, and consider using browser extensions to restrict cross-origin requests.

Public Exploit Available: Unknown

The severity of this vulnerability necessitates immediate action, as it allows for trivial remote code execution via a web browser. Organizations should prioritize updating all instances of WinML CLI to version 0.4.0 to eliminate the exposure. Failure to patch leaves systems vulnerable to malicious code injection from any website visited by a user on the affected host.