lib: avoid event override by assignment

nodejs · erights · May 13, 2025 · Jun 19, 2025 · Jun 19, 2025 · Jun 19, 2025
commit a5dce87ea3cc8486feab2f3667e61c29e4bdaafd
diff --git a/lib/events.js b/lib/events.js
@@ -330,24 +330,47 @@ EventEmitter.setMaxListeners =
 EventEmitter.init = function(opts) {
 
   if (this._events === undefined ||
-      this._events === ObjectGetPrototypeOf(this)._events) {
-    this._events = { __proto__: null };
-    this._eventsCount = 0;
-    this[kShapeMode] = false;
+    this._events === ObjectGetPrototypeOf(this)._events) {
+    ObjectDefineProperties(this, {
+      __proto__: null,
+      _events: {
+        __proto__: null,
+        value: { __proto__: null },
+      },
+      _eventCount: {
+        __proto__: null,
+        value: 0,
+      },
+      [kShapeMode]: {
+        __proto__: null,
+        value: false,
+      },
+    });
   } else {
-    this[kShapeMode] = true;
+    ObjectDefineProperty(this, kShapeMode, {
+      __proto__: null,
+      value: true,
+    });
   }
 
-  this._maxListeners ||= undefined;
-
+  ObjectDefineProperty(this, '_maxListeners', {
+    __proto__: null,
+    value: this._maxListeners || undefined,
+  });
 
   if (opts?.captureRejections) {
     validateBoolean(opts.captureRejections, 'options.captureRejections');
-    this[kCapture] = Boolean(opts.captureRejections);
+    ObjectDefineProperty(this, kCapture, {
+      __proto__: null,
+      value: Boolean(opts.captureRejections),
+    });
   } else {
     // Assigning the kCapture property directly saves an expensive
     // prototype lookup in a very sensitive hot path.
-    this[kCapture] = EventEmitter.prototype[kCapture];
+    ObjectDefineProperty(this, kCapture, {
+      __proto__: null,
+      value: Boolean(opts.captureRejections),
+    });
   }
 };