• fix(security): deepExtend (used by addResourceBundle(..., deep, overwrite)) no longer recurses into inherited properties. It checked key existence with the in operator, which walks the prototype chain, so a source key matching an inherited built-in (e.g. hasOwnProperty, toString) caused recursion into the shared Object.prototype function and, with overwrite: true, could overwrite e.g. Object.prototype.hasOwnProperty.call with a non-callable value — corrupting a shared built-in process-wide (DoS). Existence is now checked with Object.prototype.hasOwnProperty.call, so such keys are copied as plain own data instead. This complements the existing __proto__/constructor guard and is also strictly more correct for an own-property merge. Only affects applications that pass attacker-controlled data with deep: true and overwrite: true; no standard backend/integration does this. Distinct from CVE-2026-48713 / CVE-2026-48714 (different packages, setPath mechanism). Thanks to zx (Jace) for the responsible disclosure.