{"id":"CVE-2026-23830","aliases":["EUVD-2026-4897","GHSA-wxhw-j4hc-fmq6"],"status":"published","title":"SandboxJS has Sandbox Escape via Unprotected AsyncFunction Constructor","description":"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 () =\u003e {}).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.","severity":{"version":"3.1","score":10,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H","level":"critical","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-08","score":0.01219,"percentile":0.68853,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":true,"fix_available":true},"cwes":["CWE-693","CWE-913","CWE-94"],"published":"2026-01-27T19:55:11Z","modified":"2026-10-28T02:30:39Z","exploits":[{"source":"pocgithub","id":"Galaxy-sc/CVE-2026-23830-SandBreak","title":"Galaxy-sc/CVE-2026-23830-SandBreak","date":"2026-01-28","url":"https://github.com/Galaxy-sc/CVE-2026-23830-SandBreak"}],"fixes":[{"ecosystem":"npm","package":"@nyariv/sandboxjs","fixed_in":["0.8.26"],"sources":["ghsa","osv"]}],"affected":[{"source":"ghsa","ecosystem":"npm","package":"@nyariv/sandboxjs","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"0.8.26"}]}]},{"source":"osv","ecosystem":"npm","package":"@nyariv/sandboxjs","ranges":[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"0.8.26"}]}]}],"products":[{"vendor":"nyariv","product":"sandboxjs"}],"references":[{"url":"https://github.com/nyariv/SandboxJS/security/advisories/GHSA-wxhw-j4hc-fmq6","tags":["x_refsource_CONFIRM","Exploit","Vendor Advisory","advisory","web"]},{"url":"https://github.com/nyariv/SandboxJS/commit/345aee6566e47979dee5c337b925b141e7f78ccd","tags":["x_refsource_MISC","Patch","fix","web"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-23830","tags":["advisory"]},{"url":"https://github.com/advisories/GHSA-wxhw-j4hc-fmq6"},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/23xxx/CVE-2026-23830.json","tags":["advisory"]},{"url":"https://github.com/nyariv/SandboxJS","tags":["package"]}],"sources":{"cve":[{"id":"CVE-2026-23830","title":"SandboxJS has Sandbox Escape via Unprotected AsyncFunction Constructor","description":"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 () =\u003e {}).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.","status":"published","published":"2026-01-27T23:32:16.104Z","modified":"2026-01-28T15:09:44.543Z","cvss":[{"version":"3.1","score":10,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H","level":"critical","assessor":"cna"}],"cwes":["CWE-94","CWE-693","CWE-913"],"updated_at":"2026-11-02T13:42:26.790871Z"}],"euvd":[{"id":"EUVD-2026-4897","description":"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 () =\u003e {}).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.","status":"published","published":"2026-01-27T23:32:16Z","modified":"2026-01-28T15:09:44Z","cvss":[{"version":"3.1","score":10,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H","level":"critical"}],"updated_at":"2026-11-02T19:48:46.416428Z"}],"ghsa":[{"id":"GHSA-wxhw-j4hc-fmq6","title":"SandboxJS has Sandbox Escape via Unprotected AsyncFunction Constructor","description":"### 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 () =\u003e {}).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 () =\u003e {};\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 =\u003e {\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.","status":"published","published":"2026-01-27T19:55:11Z","modified":"2026-01-29T03:43:44Z","cvss":[{"version":"3.1","score":10,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H","level":"critical"}],"cwes":["CWE-94","CWE-693","CWE-913"],"updated_at":"2026-11-02T14:39:20.563096Z"}],"nvd":[{"id":"CVE-2026-23830","description":"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 () =\u003e {}).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.","status":"published","published":"2026-01-28T00:15:50.17Z","modified":"2026-06-17T10:22:10.25Z","cvss":[{"version":"3.1","score":10,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H","level":"critical","assessor":"secondary"}],"cwes":["CWE-94","CWE-693","CWE-913"],"updated_at":"2026-11-02T14:12:04.769088Z"}],"osv":[{"id":"CVE-2026-23830","title":"SandboxJS has Sandbox Escape via Unprotected AsyncFunction Constructor","description":"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 () =\u003e {}).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.","status":"published","published":"2026-01-27T23:32:16.104Z","modified":"2026-10-28T02:30:39.696476788Z","cvss":[{"version":"3.1","score":10,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H","level":"critical"}],"cwes":["CWE-693","CWE-913","CWE-94"],"updated_at":"2026-11-02T15:44:59.079784Z"},{"id":"GHSA-wxhw-j4hc-fmq6","title":"SandboxJS has Sandbox Escape via Unprotected AsyncFunction Constructor","description":"### 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 () =\u003e {}).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 () =\u003e {};\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 =\u003e {\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.","status":"published","published":"2026-01-27T19:55:11Z","modified":"2026-02-03T03:05:39.266994Z","cvss":[{"version":"3.1","score":10,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H","level":"critical"}],"cwes":["CWE-693","CWE-913","CWE-94"],"updated_at":"2026-11-02T15:46:59.131095Z"}]}}