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protected static Digester webDigester = null;

protected void init() {
  if(webDigester == null){
    webDigester = createWebDigester();
    webDigester.getParser(); // Does not use the context Classloader at initialization
  }
  // ...
}

Noncompliant Code Example

The newInstance() method is being invoked on the dateClass Class object. The issue is that the untrustedCode method can trigger the instantiation of a new class even though it should not have the permission to do so. This behavior is not caught by the security manager.

public class ExceptionExample {
   public static void untrustedCode() {
     Date now = new Date();
     Class<?> dateClass = now.getClass();
     createInstance(dateClass);
    }

    public static void createInstance(Class<?> dateClass) {
      try { // Create another Date object using the Date Class
        Object o = dateClass.newInstance();
        
        if (o instanceof Date) {
          Date d = (Date)o;
          System.out.println("The time is: " + d.toString());
        }
      }
      catch (InstantiationException ie) { System.out.println(ie.toString()); }
      catch (IllegalAccessException iae) { System.out.println(iae.toString()); }    	
    }
}

A related issue is described in SEC03-J. Do not use APIs that perform access checks against the immediate caller.

Compliant Solution

Do not accept Class, ClassLoader or Thread instances from untrusted code. If inevitable, safely acquire these instances by ensuring they come from trusted sources. Additionally, make sure to discard tainted inputs from untrusted code. Likewise, objects returned by the affected methods should not be propagated back to the untrusted code.

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