Cloneable Class Containing Sensitive Information

The code contains a class with sensitive data, but the class is cloneable. The data can then be accessed by cloning the class.


Cloneable classes are effectively open classes, since data cannot be hidden in them. Classes that do not explicitly deny cloning can be cloned by any other class without running the constructor.


The following examples help to illustrate the nature of this weakness and describe methods or techniques which can be used to mitigate the risk.

Note that the examples here are by no means exhaustive and any given weakness may have many subtle varieties, each of which may require different detection methods or runtime controls.

Example One

The following example demonstrates the weakness.

public class CloneClient {

  public CloneClient() //throws
  java.lang.CloneNotSupportedException {

    Teacher t1 = new Teacher("guddu","22,nagar road");
    // Do some stuff to remove the teacher.
    Teacher t2 = (Teacher)t1.clone();

  public static void main(String args[]) {

    new CloneClient();


class Teacher implements Cloneable {

  public Object clone() {

    try {
      return super.clone();
    catch (java.lang.CloneNotSupportedException e) {

      throw new RuntimeException(e.toString());


  public String name;
  public String clas;
  public Teacher(String name,String clas) { = name;
    this.clas = clas;



Make classes uncloneable by defining a clone function like:

public final void clone() throws java.lang.CloneNotSupportedException {
  throw new java.lang.CloneNotSupportedException();

See Also

Comprehensive Categorization: Exposed Resource

Weaknesses in this category are related to exposed resource.

SEI CERT Oracle Secure Coding Standard for Java - Guidelines 05. Object Orientation (OBJ)

Weaknesses in this category are related to the rules and recommendations in the Object Orientation (OBJ) section of the SEI CERT Oracle Secure Coding Standard for Java.

SFP Secondary Cluster: Exposed Data

This category identifies Software Fault Patterns (SFPs) within the Exposed Data cluster (SFP23).

Comprehensive CWE Dictionary

This view (slice) covers all the elements in CWE.

CWE Cross-section

This view contains a selection of weaknesses that represent the variety of weaknesses that are captured in CWE, at a level of abstraction that is likely to be useful t...

Weaknesses Introduced During Implementation

This view (slice) lists weaknesses that can be introduced during implementation.

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