CVE-2026-47686: VM2 has Missing Error.cause Sanitization that Enables Sandbox Escape to RCE

I found that handleException() in lib/setup-sandbox.js recursively sanitizes sub-errors for SuppressedError and AggregateError, but completely ignores the ES2022 Error.cause property. When sandbox code catches a host-thrown error carrying a .cause that references a host object like process, it can traverse that reference to achieve arbitrary command execution on the host.

The project’s own docs/ATTACKS.md (Defense Invariant #3, line 54) explicitly claims Error.cause is sanitized. The implementation does not match this claim.