Index: library/Zend/Json/Decoder.php
===================================================================
--- library/Zend/Json/Decoder.php	(revision 24547)
+++ library/Zend/Json/Decoder.php	(working copy)
@@ -236,6 +236,9 @@
                 // Create new StdClass and populate with $members
                 $result = new StdClass();
                 foreach ($members as $key => $value) {
+                    if ($key === '') {
+                        $key = '_empty_';
+                    }
                     $result->$key = $value;
                 }
                 break;
Index: tests/Zend/JsonTest.php
===================================================================
--- tests/Zend/JsonTest.php	(revision 24547)
+++ tests/Zend/JsonTest.php	(working copy)
@@ -887,6 +887,19 @@
         $json = Zend_Json::encode($array);
         $this->assertEquals($expected, $json);
     }
+    
+    /**
+     * @group ZF-7586
+     */
+    public function testWillDecodeStructureWithEmptyKeyToObjectProperly()
+    {
+        Zend_Json::$useBuiltinEncoderDecoder = true;
+        
+        $json = '{"":"test"}';
+        $object = Zend_Json::decode($json, Zend_Json::TYPE_OBJECT);
+        $this->assertTrue(isset($object->_empty_));
+        $this->assertEquals('test', $object->_empty_);
+    }
 
 }