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.)
CWE-486 Variant Draft
Comparison of Classes by Name
This vulnerability occurs when an application determines an object's trustworthiness or behavior solely by checking its class name. Since multiple classes can share identical names across different…
Definition
What is CWE-486?
This vulnerability occurs when an application determines an object's trustworthiness or behavior solely by checking its class name. Since multiple classes can share identical names across different packages or classloaders, this comparison can lead to using the wrong, potentially malicious, class.
Relying on class name strings for security decisions is inherently risky. Attackers can craft classes with names identical to your trusted ones, tricking your application into granting them unauthorized privileges or executing unintended code paths. This is especially problematic in environments with multiple classloaders, like application servers, where the same fully-qualified name can point to completely different implementations.
Detecting these logical flaws manually is challenging, as they depend on runtime context. While SAST tools can flag dangerous comparison patterns, Plexicus uses AI to not only identify the risk but also suggest specific, secure refactoring—such as using direct class object comparisons or verifying the classloader—saving significant manual review time and preventing impersonation attacks.
Real-world impact
Real-world CVEs caused by CWE-486
No public CVE references are linked to this CWE in MITRE's catalog yet.
How attackers exploit it
Step-by-step attacker path
- 1
In this example, the expression in the if statement compares the class of the inputClass object to a trusted class by comparing the class names.
- 2
However, multiple classes can have the same name therefore comparing an object's class by name can allow untrusted classes of the same name as the trusted class to be use to execute unintended or incorrect code. To compare the class of an object to the intended class the getClass() method and the comparison operator "==" should be used to ensure the correct trusted class is used, as shown in the following example.
- 3
In this example, the Java class, TrustedClass, overrides the equals method of the parent class Object to determine equivalence of objects of the class. The overridden equals method first determines if the object, obj, is the same class as the TrustedClass object and then compares the object's fields to determine if the objects are equivalent.
- 4
However, the equals method compares the class names of the object, obj, and the TrustedClass object to determine if they are the same class. As with the previous example using the name of the class to compare the class of objects can lead to the execution of unintended or incorrect code if the object passed to the equals method is of another class with the same name. To compare the class of an object to the intended class, the getClass() method and the comparison operator "==" should be used to ensure the correct trusted class is used, as shown in the following example.
Vulnerable code example
Vulnerable Java
In this example, the expression in the if statement compares the class of the inputClass object to a trusted class by comparing the class names.
if (inputClass.getClass().getName().equals("TrustedClassName")) {
```
// Do something assuming you trust inputClass*
*// ...*
} Secure code example
Secure Java
However, multiple classes can have the same name therefore comparing an object's class by name can allow untrusted classes of the same name as the trusted class to be use to execute unintended or incorrect code. To compare the class of an object to the intended class the getClass() method and the comparison operator "==" should be used to ensure the correct trusted class is used, as shown in the following example.
if (inputClass.getClass() == TrustedClass.class) {
```
// Do something assuming you trust inputClass*
*// ...*
} What changed: the unsafe sink is replaced (or the input is validated/escaped) so the same payload no longer triggers the weakness.
Prevention checklist
How to prevent CWE-486
- Implementation Use class equivalency to determine type. Rather than use the class name to determine if an object is of a given type, use the getClass() method, and == operator.
Detection signals
How to detect CWE-486
CWE-486
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Frequently asked questions What is CWE-486?
How serious is CWE-486?
What languages or platforms are affected by CWE-486?
How can I prevent CWE-486?
How does Plexicus detect and fix CWE-486?
Where can I learn more about CWE-486?
Frequently asked questions
What is CWE-486?
This vulnerability occurs when an application determines an object's trustworthiness or behavior solely by checking its class name. Since multiple classes can share identical names across different packages or classloaders, this comparison can lead to using the wrong, potentially malicious, class.
How serious is CWE-486?
MITRE rates the likelihood of exploit as High — this weakness is actively exploited in the wild and should be prioritized for remediation.
What languages or platforms are affected by CWE-486?
MITRE lists the following affected platforms: Java.
How can I prevent CWE-486?
Use class equivalency to determine type. Rather than use the class name to determine if an object is of a given type, use the getClass() method, and == operator.
How does Plexicus detect and fix CWE-486?
Plexicus's SAST engine matches the data-flow signature for CWE-486 on every commit. When a match is found, our Codex Remedium agent opens a fix PR with the corrected code, tests, and a one-line summary for the reviewer.
Where can I learn more about CWE-486?
MITRE publishes the canonical definition at https://cwe.mitre.org/data/definitions/486.html. You can also reference OWASP and NIST documentation for adjacent guidance.
Related weaknesses
Weaknesses related to CWE-486
CWE-1025 Parent
Comparison Using Wrong Factors
This weakness occurs when a program compares two items but checks the wrong properties or attributes. This flawed comparison leads to…
CWE-595 Sibling
Comparison of Object References Instead of Object Contents
This vulnerability occurs when code incorrectly checks if two object references point to the same memory location, rather than comparing…
Resources
Further reading
- MITRE — official CWE-486 https://cwe.mitre.org/data/definitions/486.html
- Seven Pernicious Kingdoms: A Taxonomy of Software Security Errors https://samate.nist.gov/SSATTM_Content/papers/Seven%20Pernicious%20Kingdoms%20-%20Taxonomy%20of%20Sw%20Security%20Errors%20-%20Tsipenyuk%20-%20Chess%20-%20McGraw.pdf
- The CLASP Application Security Process https://cwe.mitre.org/documents/sources/TheCLASPApplicationSecurityProcess.pdf
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