Live › vulnerability › CVE-2026-61542
Go to dashboardGearboy's optional `--mcp-http` mode binds to all network interfaces and accepts MCP requests with no authentication, Host or Origin checks, despite documentation saying it is localhost-only. A network peer can start an MCP session and invoke emulator and debugging operations, with impact described as limited to the emulator process, its debugging state and local files accepted as media.
Summary written from the sources below. Check the originals before acting.
First seen by InfraStack 2026-10-28 20:35 UTC. All times on this page are UTC.
Only installations that run Gearboy with the optional mode can be reached this way, and the flaw is in the embedded MCP transport of the desktop build. Anyone who uses Gearboy only locally, without that flag, is not exposed.
--mcp-httpNo product ranges from the sources yet.
gearboy --version or check the installed version; versions below 3.8.7 are affected.--mcp-http, and whether TCP port 7777 is listening on all interfaces (for example ss -ltnp | grep 7777).7777 to other hosts.3.8.7 or later.--mcp-http on machines reachable from a network; firewall port 7777 until patched.Each row is the first time that source carried this signal. The analyst’s rows are its own findings.
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.
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