Next.js has information disclosure in development server's Model Context Protocol endpoint

{
  "id": "5bb9acb2b4b75b096ad2edab5f63c691cbde7333dfa99fe5794f3176b8af9c3d",
  "url": "https://osv.dev/vulnerability/GHSA-39w2-rjm5-chcv",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "Next.js has information disclosure in development server's Model Context Protocol endpoint",
    "summary": "The Next.js development server (`next dev`) exposes a Model Context Protocol endpoint that does not verify which website a request originates from, allowing a malicious website visited by the developer to read sensitive development data — including the project's location on disk, source code snippets from error reports, the route inventory, and development logs. Only applications run with `next dev` are affected. Production deployments do not serve this endpoint.",
    "evidence": "osv:GHSA-39w2-rjm5-chcv",
    "products": [
      {
        "name": {
          "value": "next",
          "evidence": "/affected/0/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "16.3.8",
            "evidence": "/affected/0/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "low",
    "structured": {
      "id": "GHSA-39w2-rjm5-chcv",
      "aliases": [
        "CVE-2026-94486",
        "GHSA-39w2-rjm5-chcv"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N"
        },
        {
          "type": "CVSS_V4",
          "score": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "type": "SEMVER",
              "events": [
                {
                  "introduced": "16.0.0"
                },
                {
                  "fixed": "16.3.8"
                }
              ]
            }
          ],
          "package": {
            "name": "next",
            "purl": "pkg:npm/next",
            "ecosystem": "npm"
          },
          "database_specific": {
            "source": "https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/10/GHSA-39w2-rjm5-chcv/GHSA-39w2-rjm5-chcv.json"
          }
        }
      ],
      "modified": "2026-10-07T20:45:05.342044468Z",
      "provider": "osv",
      "references": [
        "https://github.com/vercel/next.js/security/advisories/GHSA-39w2-rjm5-chcv",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-94486",
        "https://github.com/vercel/next.js/commit/2d9f50a409312696145b82b3157aadb6b1fef476",
        "https://github.com/vercel/next.js",
        "https://github.com/vercel/next.js/releases/tag/v16.3.8"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-346"
        ],
        "severity": "LOW",
        "github_reviewed": true,
        "nvd_published_at": "2026-10-02T16:16:51Z",
        "github_reviewed_at": "2026-10-07T20:31:51Z"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-94486",
        "evidence": "/aliases"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/database_specific/severity"
  },
  "source_id": "core-osv",
  "document_id": 97265,
  "published_at": "2026-10-07T20:31:51+00:00"
}