SandboxJS has Sandbox Escape via Unprotected AsyncFunction Constructor

{
  "id": "6731acf7f6955f74a6ae3357a13180fbfe6653f3d6478bf861b9984334f52bbf",
  "url": "https://osv.dev/vulnerability/CVE-2026-23830",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "SandboxJS has Sandbox Escape via Unprotected AsyncFunction Constructor",
    "summary": "SandboxJS is a JavaScript sandboxing library. Versions prior to 0.8.26 have a sandbox escape vulnerability due to `AsyncFunction` not being isolated in `SandboxFunction`. The 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. However, before version 0.8.26, 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`). In `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. Constructors 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). Version 0.8.26 patches this vulnerability.",
    "evidence": "osv:CVE-2026-23830",
    "products": [],
    "severity": "critical",
    "structured": {
      "id": "CVE-2026-23830",
      "aliases": [
        "CVE-2026-23830",
        "GHSA-wxhw-j4hc-fmq6"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/nyariv/sandboxjs",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "354229c64992478dc43ca9345543b5fed83ccf66"
                },
                {
                  "fixed": "345aee6566e47979dee5c337b925b141e7f78ccd"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "cpe": "cpe:2.3:a:nyariv:sandboxjs:*:*:*:*:*:node.js:*:*",
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "0.8.26"
                      }
                    ],
                    "source": "CPE_RANGE"
                  },
                  {
                    "range": [
                      {
                        "fixed": "345aee6566e47979dee5c337b925b141e7f78ccd"
                      }
                    ],
                    "source": "REFERENCES_COMMIT"
                  }
                ]
              }
            }
          ],
          "versions": [
            "0.8.24-2",
            "0.8.24-1",
            "0.8.24",
            "0.8.23.3",
            "0.8.23-1",
            "0.8.23.2",
            "0.8.23",
            "0.8.22",
            "0.8.21",
            "0.8.20",
            "0.8.19",
            "0.8.18",
            "0.8.17",
            "0.8.16",
            "0.8.15.1",
            "0.8.15",
            "0.8.14",
            "0.8.12",
            "0.8.11",
            "0.8.10",
            "0.8.9",
            "0.8.8",
            "0.8.7",
            "0.8.6",
            "0.8.5",
            "0.8.4",
            "0.8.3",
            "0.8.2",
            "0.8.0",
            "0.7.1",
            "0.7.0",
            "0.6.2",
            "0.6.1",
            "0.6.0",
            "0.5.3",
            "0.5.2",
            "0.5.0"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-23830.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:39.696476788Z",
      "provider": "osv",
      "references": [
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/23xxx/CVE-2026-23830.json",
        "https://github.com/nyariv/SandboxJS/security/advisories/GHSA-wxhw-j4hc-fmq6",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-23830",
        "https://github.com/nyariv/SandboxJS/commit/345aee6566e47979dee5c337b925b141e7f78ccd"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-693",
          "CWE-913",
          "CWE-94"
        ],
        "cna_assigner": "GitHub_M",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/23xxx/CVE-2026-23830.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-23830",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 507035,
  "published_at": "2026-01-27T23:32:16.104+00:00"
}