Fix prototype pollution vulnerability

Author: aearly

lib/internal/iterator.js

@@ -26,6 +26,9 @@ function createObjectIterator(obj) {
     var len = okeys.length;
     return function next() {
         var key = okeys[++i];
+        if (key === '__proto__') {
+            return next();
+        }
         return i < len ? {value: obj[key], key} : null;
     };
 }

test/mapValues.js

@@ -60,6 +60,17 @@ describe('mapValues', () => {
                 done();
             }, 50);
         });
+
+        it('prototype pollution', (done) => {
+            var input = JSON.parse('{"a": 1, "b": 2, "__proto__": { "exploit": true }}');
+
+            async.mapValues(input, (val, key, next) => {
+                next(null, val)
+            }, (err, result) => {
+                expect(result.exploit).to.equal(undefined)
+                done(err);
+            })
+        })
     });
 
     context('mapValues', () => {