CVE-2026-61542 (GCVE-0-2026-61542)
Vulnerability from cvelistv5
Published
2026-10-28 19:48
Modified
2026-10-28 19:48
CWE
  • CWE-306 - Missing Authentication for Critical Function
Summary
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.
Impacted products
Vendor Product Version
drhelius Gearboy Version: < 3.8.7
Create a notification for this product.
Show details on NVD website


{
  "containers": {
    "cna": {
      "affected": [
        {
          "product": "Gearboy",
          "vendor": "drhelius",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 3.8.7"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "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."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "attackComplexity": "LOW",
            "attackVector": "NETWORK",
            "availabilityImpact": "LOW",
            "baseScore": 8.6,
            "baseSeverity": "HIGH",
            "confidentialityImpact": "LOW",
            "integrityImpact": "HIGH",
            "privilegesRequired": "NONE",
            "scope": "UNCHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:L",
            "version": "3.1"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-306",
              "description": "CWE-306: Missing Authentication for Critical Function",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-28T19:48:42.991Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/drhelius/Gearboy/security/advisories/GHSA-fmvx-487g-mrww",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/drhelius/Gearboy/security/advisories/GHSA-fmvx-487g-mrww"
        },
        {
          "name": "https://github.com/drhelius/Gearboy/commit/e2ead98e2fac41e9df5a499e9e421c6a0e73f1bc",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/drhelius/Gearboy/commit/e2ead98e2fac41e9df5a499e9e421c6a0e73f1bc"
        },
        {
          "name": "https://github.com/drhelius/Gearboy/releases/tag/3.8.7",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/drhelius/Gearboy/releases/tag/3.8.7"
        }
      ],
      "source": {
        "advisory": "GHSA-fmvx-487g-mrww",
        "discovery": "UNKNOWN"
      },
      "title": "Gearboy advisory / Gearsystem body: Unauthenticated network exposure of MCP HTTP tools"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-61542",
    "datePublished": "2026-10-28T19:48:42.991Z",
    "dateReserved": "2026-07-10T16:27:03.093Z",
    "dateUpdated": "2026-10-28T19:48:42.991Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


Log in or create an account to share your comment.




Tags
Taxonomy of the tags.


Loading…

Loading…

Loading…

Sightings

Author Source Type Date

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
  • Confirmed: The vulnerability is confirmed from an analyst perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
  • Patched: This vulnerability was successfully patched by the user reporting the sighting.
  • Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
  • Not confirmed: The user expresses doubt about the veracity of the vulnerability.
  • Not patched: This vulnerability was not successfully patched by the user reporting the sighting.


Loading…

Loading…