CVE-2026-23830
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedSandboxJS 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.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · high confidenceSandboxJS versions before 0.8.26 fail to map `AsyncFunction`, `GeneratorFunction`, and `AsyncGeneratorFunction` in their safe-replacement map. Since these constructors can be accessed via `.constructor` on function instances created inside the sandbox, malicious code can obtain the native host `AsyncFunction` constructor, which creates functions executing in the global (unsandboxed) scope, bypassing all sandbox restrictions and achieving Remote Code Execution.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data< 0.8.26CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- Low
- Privileges
- None
- User interaction
- None
- Scope
- Changed
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Check installed SandboxJS versionRun `npm list sandboxjs` or inspect your project's package.json and node_modules/sandboxjs/package.json version fieldAffected if The version listed is less than 0.8.26 (e.g., 0.8.25, 0.8.0, etc.)
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Verify AsyncFunction mapping in isolation configurationInspect your SandboxJS initialization code or configuration for the isolation/safe-replacement map. Look for entries mapping AsyncFunction, GeneratorFunction, and AsyncGeneratorFunction to safe replacements.Affected if The isolation map does NOT contain entries for AsyncFunction, GeneratorFunction, and AsyncGeneratorFunction, or these constructors are mapped to unsafe native implementations.
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Test sandbox isolation with async function constructor accessCreate a test script that instantiates a sandbox, creates an async function inside it, and attempts to access fn.constructor to retrieve the AsyncFunction constructor. Then try executing a function via that constructor in the global scope.Affected if Accessing .constructor on an async function created inside the sandbox returns the native host AsyncFunction (or GeneratorFunction/AsyncGeneratorFunction), allowing code execution outside sandbox boundaries.
You are affected if your SandboxJS version is below 0.8.26 AND the AsyncFunction, GeneratorFunction, or AsyncGeneratorFunction constructors are accessible from within sandboxed code, enabling code execution in the global host scope.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
dbcve · scoped0.8.26
Upgrade SandboxJS to version 0.8.26 or later, which includes mappings for AsyncFunction, GeneratorFunction, and AsyncGeneratorFunction in the safe-replacement map.
0.8.26
- Check the current version of sandboxjs installed in your project (e.g., npm list sandboxjs or grep sandboxjs package.json)
- Update the sandboxjs dependency in your package.json to version 0.8.26 or higher (e.g., npm install [email protected] or npm update sandboxjs)
- Run the package manager install command to install the updated version (npm install, yarn install, or pnpm install depending on your setup)
- Verify the installed version is 0.8.26 or later using npm list sandboxjs
- Test that your application functionality still works correctly after the upgrade
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation2.0 h
- Implementation1.0 h
- Testing4.0 h
- Review / QA2.0 h
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Free · runs locallyCheck whether your project pulls in CVE-2026-23830 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2026-23830 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Version or environment caveats, and links to real fixes
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