1. Vulnerability Description

If the method that returns the mutable type returns an immutable collection and that value is used, a runtime error may occur.

2. Vulnerability Countermeasure

You must change the return value to immutable or copy the collection to use.

3. Sample Code

• Vulnerable Code

  public List<String> getSomeList() {
    ImmutableList<String> l = foo(...);
    return l;
  }

• Safe Code

  public ImmutableList<String> getSomeList() {
    ImmutableList<String> l = foo(...);
    return l;
  }