Code:  mrb_class_real(struct RClass* cl)
 {
  if (cl == 0)
    return NULL;
   while ((cl->tt == MRB_TT_SCLASS) || (cl->tt == MRB_TT_ICLASS)) {
     cl = cl->super;
   }
   return cl;
 }

Vulnerability Type: 
CWE ID: CWE-476
Summary: An issue was discovered in mruby 1.4.1. There is a NULL pointer dereference in mrb_class_real because *class BasicObject* is not properly supported in class.c.
Commit Message: `mrb_class_real()` did not work for `BasicObject`; fix #4037