CVE-2026-61542
Dashboard / Vulnerabilities / CVE-2026-61542
Summary: Gearboy advisory / Gearsystem body: Unauthenticated network exposure of MCP HTTP tools
Details: 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.
References: https://github.com/drhelius/Gearboy/releases/tag/3.8.7, https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/61xxx/CVE-2026-61542.json, https://github.com/drhelius/Gearboy/security/advisories/GHSA-fmvx-487g-mrww, https://nvd.nist.gov/vuln/detail/CVE-2026-61542, https://github.com/drhelius/Gearboy/commit/e2ead98e2fac41e9df5a499e9e421c6a0e73f1bc
Affected packages
Package
Name:
Purl:
