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CVE-2026-61542— Gearboy advisory / Gearsystem body: Unauthenticated network exposure of MCP HTTP tools

Quick assessment

Affected
drhelius Gearboy
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Gearboy 是一款支持 Game Boy、Game Boy Color 和 Super Game Boy 的模拟器与调试器，其内部集成了 MCP（模型上下文协议）服务器。受影响的组件 Gearsystem 提供了一个可选的 模式，该模式会接受来自任何可访问网络对等节点的未认证 MCP 请求，尽管其文档和日志中声称仅限制在本地主机（localhost）。在相关传输层文件 中，套接字绑定的是 （通常监听端口 7777），且发往 端点的 POST 请求在未经过 、 或 校验的情况下即可直达调度器。响应头和 OPTIO

CVSS 8.6 · High
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I. Basic Information for CVE-2026-61542

Vulnerability Information
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Vulnerability Title
Gearboy advisory / Gearsystem body: Unauthenticated network exposure of MCP HTTP tools
Source: CVE Program / CVE List V5
Vulnerability Description
Gearboy is a Game Boy, Game Boy Color, and Super Game Boy emulator and debugger with an embedded MCP server. Gearsystem, the affected component, has an optional `--mcp-http` mode that accepts unauthenticated MCP requests from any reachable network peer despite localhost-only documentation and logging. In the described `platforms/shared/desktop/mcp/mcp_transport.h` transport, the socket binds `INADDR_ANY`, normally on port 7777, and POST requests to `/mcp` reach dispatch without `Authorization`, `Host`, or `Origin` checks. Responses and OPTIONS advertise `Access-Control-Allow-Origin: *`. A peer can initialize an MCP session and invoke exposed emulator/debugging operations; even a garbage bearer token does not block dispatch, while a loopback-bind negative control prevents network access. The reported impact is bounded to the emulator process, debugging state, and local files accepted as media, rather than demonstrated host code execution. Gearboy 3.8.7 contains a patch.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:L
Source: CVE Program / CVE List V5
Vulnerability Type
关键功能的认证机制缺失
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
drhelius Gearboy < 3.8.7 -

II. Public POCs for CVE-2026-61542

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III. Intelligence Information for CVE-2026-61542

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Other References for CVE-2026-61542 (3)

IV. Related Vulnerabilities

Same weakness: CWE-306