SandboxJS is a JavaScript sandboxing library. Prior to 0.8.36, a scope modification vulnerability exists in @nyariv/sandboxjs. The vulnerability allows untrusted sandboxed code to leak internal interpreter objects through the new operator, exposing sandbox scope objects in the scope hierarchy to untrusted code; an unexpected and undesired exploit. While this could allow modifying scopes inside the sandbox, code evaluation remains sandboxed and prototypes remain protected throughout the execution. This vulnerability is fixed in 0.8.36.

Affected: npm: @nyariv/sandboxjs

## Description

A scope modification vulnerability exists in `@nyariv/sandboxjs` version 0.8.35 and below. The vulnerability allows untrusted sandboxed code to leak internal interpreter objects through the `new` operator, exposing sandbox scope objects in the scope hierarchy to untrusted code; an unexpected and undesired exploit. While this could allow modifying scopes inside the sandbox, code evaluation remains sandboxed and prototypes remain protected throughout the execution.

## Vulnerable Code Location

### Primary: The `New` Operator Handler

**File**: `src/executor.ts`, lines 1275–1280

```typescript addOps<new (...args: unknown[]) => unknown, unknown[]>( LispType.New, ({ done, a, b, context }) => { if (!context.ctx.globalsWhitelist.has(a) && !context.ctx.sandboxedFunctions.has(a)) { throw new SandboxAccessError(`Object construction not allowed: ${a.constructor.name}`); } done(undefined, new a(...b)); // ← b is NOT sanitized, return is NOT sanitized }, ); ```

This handler has **two missing sanitization steps**:

1. **Arguments (`b`) are not passed through `valueOrProp()`** — Constructor arguments contain raw `Prop` objects (internal interpreter wrappers) instead of extracted values.

2. **Return value is not passed through `getGlobalProp()` or `sanitizeArray()`** — The constructed object is returned directly to the execution tree without any sanitization.

### Comparison: The `Call` Handler (Correctly Implemented)

**File**: `src/executor.ts`…