CVE-2026-47139: Vm2 NodeVM Network Builtin Exclusions Bypass Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-r9pm-gxmw-wv6p",
  "modified" : "2026-06-12T19:30:09Z",
  "published" : "2026-05-29T18:08:06Z",
  "aliases" : [ "CVE-2026-47139" ],
  "summary" : "NodeVM network builtin exclusions bypass via internal _http_client and _http_server",
  "details" : "## Summary\n\n`NodeVM` supports excluding public network builtins from the wildcard builtin option. With this configuration direct access to `http`, `https`, `http2`, `net`, `dgram`, `tls`, `dns`, and `dns/promises` is blocked.\n\nHowever, Node.js also exposes underscored internal HTTP builtins such as `_http_client` and `_http_server`. These are not blocked when the public modules are excluded.\n\nSandboxed code can use these internal builtins to make outbound HTTP requests and open listening HTTP sockets even though the public network modules are denied.\n\n**Note**: This is not host RCE. It is a network capability bypass that can lead to SSRF-style access to internal services.\n\n## Details\n\nThe wildcard builtin expansion is based on Node.js builtin module names:\n\n```js\nconst BUILTIN_MODULES = (nmod.builtinModules || Object.getOwnPropertyNames(process.binding('natives')))\n  .filter(s=>!s.startsWith('internal/') && !DANGEROUS_BUILTINS.has(s));\n```\n\nPublic modules can be excluded with `-name`:\n\n```js\nif (builtins.indexOf(`-${name}`) === -1) {\n  addDefaultBuiltin(res, name, hostRequire);\n}\n```\n\nBut excluding `http` and `net` does not exclude internal siblings such as:\n\n```text\n_http_client\n_http_server\n_tls_wrap\n```\n\nThese internal modules expose network primitives.\n\nConfirmed examples:\n\n1. `require('_http_client').ClientRequest(...)` performs an outbound HTTP request to a host-local service while `http` and `net` are blocked.\n2. `require('_http_server').Server(...).listen(...)` opens a listening HTTP socket while `http` and `net` are blocked.\n\n## PoC\n\nTested on:\n\n```text\nvm2: 3.11.2\nNode.js: v25.9.0\n```\n\nRun from the vm2 repository root:\n\n```bash\nnode poc/internal-http-builtin-network-bypass.js\n```\n[internal-http-builtin-network-bypass.js](https://github.com/user-attachments/files/27571182/internal-http-builtin-network-bypass.js)\n\n\nThe PoC first confirms the intended restrictions work then bypasses them:\n\n```text\nrequire(\"_http_client\").ClientRequest(...)\n```\n\nThis performs an HTTP request to a host-local service and reads the response.\n\nIt also confirms:\n\n```text\nrequire(\"_http_server\").Server(...).listen(0)\n```\n\nThis opens a listening HTTP socket from inside the sandbox.\n\n<img width=\"951\" height=\"623\" alt=\"Screenshot 2026-05-10 at 1 07 39 PM\" src=\"https://github.com/user-attachments/assets/21bfb1ff-dd15-423a-92c4-0337cd07816c\" />\n\n## Impact\n\nAn attacker who can run untrusted JavaScript inside `NodeVM` with this affected builtin configuration can regain network access even when the application attempted to block network modules.\n\nThis can allow SSRF-style access to localhost services, metadata endpoints, internal admin panels, or other network resources reachable from the host process.\n\n## Suggested fix\n\nTreat underscored internal network modules as dangerous or link their availability to the public module they wrap.\n\nAt minimum, exclude related internal modules such as:\n\n```text\n_http_agent\n_http_client\n_http_common\n_http_incoming\n_http_outgoing\n_http_server\n_tls_common\n_tls_wrap\n```\n\nAlternatively, deny underscored Node.js internals from wildcard builtin expansion by default.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "npm",
      "name" : "vm2"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "3.11.4"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 3.11.3"
    }
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/patriksimek/vm2/security/advisories/GHSA-r9pm-gxmw-wv6p"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-47139"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/patriksimek/vm2/commit/436053e30eecbabd487e2fd2959c137ac34e2bb1"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/patriksimek/vm2"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/patriksimek/vm2/releases/tag/v3.11.4"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-693" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-05-29T18:08:06Z",
    "nvd_published_at" : "2026-06-12T15:16:28Z"
  }
}