Comparison of Object References Instead of Object Contents

Incomplete Variant

Structure: Simple

Description

The product compares object references instead of the contents of the objects themselves, preventing it from detecting equivalent objects.

Extended Description

For example, in Java, comparing objects using == usually produces deceptive results, since the == operator compares object references rather than values; often, this means that using == for strings is actually comparing the strings' references, not their values.

Common Consequences 1

Scope: Other

Impact: Varies by Context

This weakness can lead to erroneous results that can cause unexpected application behaviors.

Detection Methods 1

Automated Static AnalysisHigh

Automated static analysis, commonly referred to as Static Application Security Testing (SAST), can find some instances of this weakness by analyzing source code (or binary/compiled code) without having to execute it. Typically, this is done by building a model of data flow and control flow, then searching for potentially-vulnerable patterns that connect "sources" (origins of input) with "sinks" (destinations where the data interacts with external components, a lower layer such as the OS, etc.)

Potential Mitigations 1

Phase: Implementation

In Java, use the equals() method to compare objects instead of the == operator. If using ==, it is important for performance reasons that your objects are created by a static factory, not by a constructor.

Demonstrative Examples 2

ID : DX-60

In the example below, two Java String objects are declared and initialized with the same string values. An if statement is used to determine if the strings are equivalent.

Code Example:Bad
Java
java

However, the if statement will not be executed as the strings are compared using the "==" operator. For Java objects, such as String objects, the "==" operator compares object references, not object values. While the two String objects above contain the same string values, they refer to different object references, so the System.out.println statement will not be executed. To compare object values, the previous code could be modified to use the equals method:

Code Example:Good
Java
java

In the following Java example, two BankAccount objects are compared in the isSameAccount method using the == operator.

Code Example:Bad
Java
java

Using the == operator to compare objects may produce incorrect or deceptive results by comparing object references rather than values. The equals() method should be used to ensure correct results or objects should contain a member variable that uniquely identifies the object.

The following example shows the use of the equals() method to compare the BankAccount objects and the next example uses a class get method to retrieve the bank account number that uniquely identifies the BankAccount object to compare the objects.

Code Example:Good
Java
java

References 1

Equality comparisons and sameness

Mozilla MDN

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Equality_comparisons_and_sameness(2025-08-04)

ID: REF-954

Applicable Platforms

Languages:

Java : UndeterminedJavaScript : UndeterminedPHP : UndeterminedNot Language-Specific : Undetermined

Modes of Introduction

Implementation

Related Weaknesses

ChildOf:

Comparison Using Wrong Factors (CWE-1025)

Taxonomy Mapping

The CERT Oracle Secure Coding Standard for Java (2011)
The CERT Oracle Secure Coding Standard for Java (2011)
The CERT Oracle Secure Coding Standard for Java (2011)