Medium · published September 17, 2026
vm2 is a sandbox for running untrusted Node.js code. In versions <= 3.11.7, NodeVM exposes the host `util` module to the sandbox as an unfiltered shallow copy (`Object.assign({}, util)` in `defaultBuiltinLoaderUtil`), and the deprecated `sys` builtin (an alias of host `util`) is exposed through the generic builtin loader. On Node.js >= 22.9 this hands sandboxed code `util.getCallSites()`, a programmatic stack-introspection API that returns the host process's full call stack, including absolute file paths, function names, and line numbers for vm2 bridge internals and the embedding application's entrypoint. This bypasses the host-frame redaction introduced for GHSA-v27g-jcqj-v8rw, which only applies to the `Error.prepareStackTrace` formatting channel. The issue is fixed in vm2 3.11.8.