--- a/src/share/classes/java/io/ObjectInputStream.java	Wed Apr 10 23:02:46 2013 +0100
+++ b/src/share/classes/java/io/ObjectInputStream.java	Mon Mar 11 15:07:19 2013 +0100
@@ -41,6 +41,7 @@
 import java.util.concurrent.ConcurrentMap;
 import java.util.concurrent.atomic.AtomicBoolean;
 import static java.io.ObjectStreamClass.processQueue;
+import sun.reflect.misc.ReflectUtil;
 
 /**
  * An ObjectInputStream deserializes primitive data and objects previously
@@ -1519,6 +1520,12 @@
         }
     }
 
+    private boolean isCustomSubclass() {
+        // Return true if this class is a custom subclass of ObjectInputStream
+        return getClass().getClassLoader()
+                    != ObjectInputStream.class.getClassLoader();
+    }
+
     /**
      * Reads in and returns class descriptor for a dynamic proxy class.  Sets
      * passHandle to proxy class descriptor's assigned handle.  If proxy class
@@ -1548,6 +1555,15 @@
         try {
             if ((cl = resolveProxyClass(ifaces)) == null) {
                 resolveEx = new ClassNotFoundException("null class");
+            } else if (!Proxy.isProxyClass(cl)) {
+                throw new InvalidClassException("Not a proxy");
+            } else {
+                // ReflectUtil.checkProxyPackageAccess makes a test
+                // equivalent to isCustomSubclass so there's no need
+                // to condition this call to isCustomSubclass == true here.
+                ReflectUtil.checkProxyPackageAccess(
+                        getClass().getClassLoader(),
+                        cl.getInterfaces());
             }
         } catch (ClassNotFoundException ex) {
             resolveEx = ex;
@@ -1589,9 +1605,12 @@
         Class cl = null;
         ClassNotFoundException resolveEx = null;
         bin.setBlockDataMode(true);
+        final boolean checksRequired = isCustomSubclass();
         try {
             if ((cl = resolveClass(readDesc)) == null) {
                 resolveEx = new ClassNotFoundException("null class");
+            } else if (checksRequired) {
+                ReflectUtil.checkPackageAccess(cl);
             }
         } catch (ClassNotFoundException ex) {
             resolveEx = ex;