--- a/jdk/src/share/classes/java/io/ObjectOutputStream.java	Mon Apr 22 10:22:59 2013 +0100
+++ b/jdk/src/share/classes/java/io/ObjectOutputStream.java	Mon Apr 22 10:55:14 2013 +0100
@@ -36,6 +36,7 @@
 import java.util.concurrent.ConcurrentMap;
 import static java.io.ObjectStreamClass.processQueue;
 import java.io.SerialCallbackContext;
+import sun.reflect.misc.ReflectUtil;
 
 /**
  * An ObjectOutputStream writes primitive data types and graphs of Java objects
@@ -1228,6 +1229,12 @@
         }
     }
 
+    private boolean isCustomSubclass() {
+        // Return true if this class is a custom subclass of ObjectOutputStream
+        return getClass().getClassLoader()
+                   != ObjectOutputStream.class.getClassLoader();
+    }
+
     /**
      * Writes class descriptor representing a dynamic proxy class to stream.
      */
@@ -1245,6 +1252,9 @@
         }
 
         bout.setBlockDataMode(true);
+        if (isCustomSubclass()) {
+            ReflectUtil.checkPackageAccess(cl);
+        }
         annotateProxyClass(cl);
         bout.setBlockDataMode(false);
         bout.writeByte(TC_ENDBLOCKDATA);
@@ -1271,6 +1281,9 @@
 
         Class<?> cl = desc.forClass();
         bout.setBlockDataMode(true);
+        if (isCustomSubclass()) {
+            ReflectUtil.checkPackageAccess(cl);
+        }
         annotateClass(cl);
         bout.setBlockDataMode(false);
         bout.writeByte(TC_ENDBLOCKDATA);

--- a/jdk/src/share/classes/java/io/ObjectStreamClass.java	Mon Apr 22 10:22:59 2013 +0100
+++ b/jdk/src/share/classes/java/io/ObjectStreamClass.java	Mon Apr 22 10:55:14 2013 +0100
@@ -50,6 +50,7 @@
 import java.util.concurrent.ConcurrentMap;
 import sun.misc.Unsafe;
 import sun.reflect.ReflectionFactory;
+import sun.reflect.misc.ReflectUtil;
 
 /**
  * Serialization's descriptor for classes.  It contains the name and
@@ -259,6 +260,13 @@
      * @return  the <code>Class</code> instance that this descriptor represents
      */
     public Class<?> forClass() {
+        if (cl == null) {
+            return null;
+        }
+        ClassLoader ccl = ObjectStreamField.getCallerClassLoader();
+        if (ReflectUtil.needsPackageAccessCheck(ccl, cl.getClassLoader())) {
+            ReflectUtil.checkPackageAccess(cl);
+        }
         return cl;
     }
 

--- a/jdk/src/share/classes/java/io/ObjectStreamField.java	Mon Apr 22 10:22:59 2013 +0100
+++ b/jdk/src/share/classes/java/io/ObjectStreamField.java	Mon Apr 22 10:55:14 2013 +0100
@@ -26,6 +26,8 @@
 package java.io;
 
 import java.lang.reflect.Field;
+import sun.reflect.Reflection;
+import sun.reflect.misc.ReflectUtil;
 
 /**
  * A description of a Serializable field from a Serializable class.  An array
@@ -158,9 +160,31 @@
      *          serializable field
      */
     public Class<?> getType() {
+        ClassLoader ccl = getCallerClassLoader();
+        if (ReflectUtil.needsPackageAccessCheck(ccl, type.getClassLoader())) {
+            ReflectUtil.checkPackageAccess(type);
+        }
         return type;
     }
 
+    // Returns the invoker's class loader.
+    // This is package private because it is accessed from ObjectStreamClass.
+    // NOTE: This must always be invoked when there is exactly one intervening
+    // frame from the core libraries on the stack between this method's
+    // invocation and the desired invoker. The frame count of 3 is determined
+    // as follows:
+    //
+    // 0: Reflection.getCallerClass
+    // 1: getCallerClassLoader()
+    // 2: ObjectStreamField.getType() or ObjectStreamClass.forClass()
+    // 3: the caller we want to check
+    //
+    // NOTE: copied from java.lang.ClassLoader and modified.
+    static ClassLoader getCallerClassLoader() {
+        Class caller = Reflection.getCallerClass(3);
+        return caller.getClassLoader();
+    }
+
     /**
      * Returns character encoding of field type.  The encoding is as follows:
      * <blockquote><pre>