We are using hibernate-validation 4.3.1-Final and a PermGen space exception occurs after a few redeploys. We have analyzed the heap dump using Eclipse MAT and saw that it seems to be connected with Hibernate Validation. There seems to be a reference stored in providersPerClassloader. I had a look at the source and saw these lines:

//cache per classloader for an appropriate discovery
//keep them in a weak hash map to avoid memory leaks and allow proper hot redeployment
private static final Map<ClassLoader, List<ValidationProvider<?>>> providersPerClassloader = new WeakHashMap<ClassLoader, List<ValidationProvider<?>>>();

I guess the issue is known but still not resolved correctly.