An unauthenticated arbitrary file write vulnerability in the Flux159 mcp-game-asset-gen MCP interface allows remote attackers to create or overwrite system files.

This vulnerability is a path traversal and file write flaw located in the image_to_3d_async function of src/index.ts, where unauthenticated remote attackers can manipulate the statusFile argument without proper path validation.

Successful exploitation of this vulnerability allows unauthenticated attackers to write arbitrary JSON data to writable filesystem locations, leading to potential configuration tampering, log corruption, or application service disruption. While the CVSS score is 7.3, the ability to arbitrarily overwrite files poses a severe integrity and availability risk to the hosting environment if the application runs with elevated privileges.

Immediate Action: Restrict network access to the Model Context Protocol (MCP) server, ensure it is not exposed to untrusted clients, and disable the vulnerable image_to_3d_async tool until a vendor patch is released.

Proactive Monitoring: Monitor filesystem activity for unexpected file creation or modification events outside the intended asset output directory, and review server access logs for anomalous tool invocation patterns.

Compensating Controls: Run the MCP server process under a dedicated, low-privilege service account with a strictly restricted working directory to limit the blast radius of any potential file write operations.

Public Exploit Available: Yes, a published proof-of-concept exists in the referenced GitHub issue report.

Security teams must treat this vulnerability with high urgency despite the lack of active in-the-wild exploitation reports. Administrators should immediately isolate the affected MCP interface behind trusted networks or firewalls and enforce strict privilege reduction on the host operating system.