diff -r 1aa9beac610e -r 821bfc24d750 src/jdk.jfr/share/classes/jdk/jfr/internal/SecuritySupport.java
--- a/src/jdk.jfr/share/classes/jdk/jfr/internal/SecuritySupport.java	Thu Oct 04 16:39:07 2018 +0200
+++ b/src/jdk.jfr/share/classes/jdk/jfr/internal/SecuritySupport.java	Thu Oct 04 08:45:21 2018 -0700
@@ -31,6 +31,7 @@
 import java.io.InputStream;
 import java.io.RandomAccessFile;
 import java.io.Reader;
+import java.lang.invoke.MethodHandles;
 import java.lang.reflect.Constructor;
 import java.lang.reflect.Field;
 import java.lang.reflect.Method;
@@ -71,6 +72,7 @@
  */
 public final class SecuritySupport {
     private final static Unsafe unsafe = Unsafe.getUnsafe();
+    private final static MethodHandles.Lookup LOOKUP = MethodHandles.lookup();
     private final static Module JFR_MODULE = Event.class.getModule();
     public  final static SafePath JFC_DIRECTORY = getPathInProperty("java.home", "lib/jfr");
 
@@ -381,8 +383,17 @@
         unsafe.ensureClassInitialized(clazz);
     }
 
-    static Class<?> defineClass(String name, byte[] bytes, ClassLoader classLoader) {
-        return unsafe.defineClass(name, bytes, 0, bytes.length, classLoader, null);
+    static Class<?> defineClass(Class<?> lookupClass, byte[] bytes) {
+        return AccessController.doPrivileged(new PrivilegedAction<>() {
+            @Override
+            public Class<?> run() {
+                try {
+                    return MethodHandles.privateLookupIn(lookupClass, LOOKUP).defineClass(bytes);
+                } catch (IllegalAccessException e) {
+                    throw new InternalError(e);
+                }
+            }
+        });
     }
 
     static Thread createThreadWitNoPermissions(String threadName, Runnable runnable) {