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-500 Variante Borrador
Public Static Field Not Marked Final
This vulnerability occurs when a class exposes a public static field without declaring it as final, allowing unintended modification from anywhere in the application.
Definición
What is CWE-500?
This vulnerability occurs when a class exposes a public static field without declaring it as final, allowing unintended modification from anywhere in the application.
Public static fields act as global variables within your application's classloader. Because they are public, any other class can directly read and, crucially, modify their value without using proper getter or setter methods. This bypasses any validation, logging, or synchronization logic you might have in place, leading to unpredictable state changes that are difficult to trace and debug.
To prevent this, you should mark any necessary public static fields as `final` to make them constants. If a field truly needs to be mutable, consider making it private and providing controlled access through static methods, applying the principle of encapsulation even to static members to maintain data integrity and thread safety.
Impacto en el mundo real
Real-world CVEs caused by CWE-500
Todavía no hay CVEs públicos enlazados a esta CWE en el catálogo de MITRE.
Cómo lo explotan los atacantes
Ruta del atacante paso a paso
- 1
Identifica una ruta de código que maneje entrada no confiable sin validación.
- 2
Crea un payload que ejercite el comportamiento inseguro — inyección, traversal, overflow o abuso de lógica.
- 3
Envía el payload a través de una solicitud normal y observa la reacción de la aplicación.
- 4
Itera hasta que la respuesta filtre datos, ejecute código del atacante o escale privilegios.
Ejemplo de código vulnerable
Vulnerable C++
The following examples use of a public static String variable to contain the name of a property/configuration file for the application.
class SomeAppClass {
public:
static string appPropertiesConfigFile = "app/properties.config";
...
} Ejemplo de código seguro
Secure C++
Having a public static variable that is not marked final (constant) may allow the variable to the altered in a way not intended by the application. In this example the String variable can be modified to indicate a different on nonexistent properties file which could cause the application to crash or caused unexpected behavior.
class SomeAppClass {
public:
static const string appPropertiesConfigFile = "app/properties.config";
...
} What changed: the unsafe sink is replaced (or the input is validated/escaped) so the same payload no longer triggers the weakness.
Lista de prevención
How to prevent CWE-500
- Architecture and Design Clearly identify the scope for all critical data elements, including whether they should be regarded as static.
- Implementation Make any static fields private and constant. A constant field is denoted by the keyword 'const' in C/C++ and ' final' in Java
Señales de detección
How to detect CWE-500
CWE-500
Don't catalog this weakness. Prove it's reachable.
Plexicus turns CWE catalogs into evidence: every CWE-pattern is matched against your real code graph, reach is proven on a sandbox clone, and verified findings ship as reviewed PRs.
Preguntas frecuentes ¿Qué es CWE-500?
¿Qué gravedad tiene CWE-500?
¿Qué lenguajes o plataformas se ven afectados por CWE-500?
¿Cómo puedo prevenir CWE-500?
¿Cómo detecta y corrige Plexicus CWE-500?
¿Dónde puedo aprender más sobre CWE-500?
Frequently asked questions
¿Qué es CWE-500?
This vulnerability occurs when a class exposes a public static field without declaring it as final, allowing unintended modification from anywhere in the application.
¿Qué gravedad tiene CWE-500?
MITRE califica la probabilidad de explotación como Alta — esta debilidad se explota activamente en la práctica y debe priorizarse para su remediación.
¿Qué lenguajes o plataformas se ven afectados por CWE-500?
MITRE lists the following affected platforms: C++, Java.
¿Cómo puedo prevenir CWE-500?
Clearly identify the scope for all critical data elements, including whether they should be regarded as static. Make any static fields private and constant. A constant field is denoted by the keyword 'const' in C/C++ and ' final' in Java
¿Cómo detecta y corrige Plexicus CWE-500?
El motor SAST de Plexicus detecta la firma de flujo de datos para CWE-500 en cada commit. Cuando hay coincidencia, nuestro agente Codex Remedium abre un PR de corrección con el código corregido, las pruebas y un resumen de una línea para el revisor.
¿Dónde puedo aprender más sobre CWE-500?
MITRE publica la definición canónica en https://cwe.mitre.org/data/definitions/500.html. También puedes consultar la documentación de OWASP y NIST para guías relacionadas.
Debilidades relacionadas
Weaknesses related to CWE-500
¿Listo para validar lo que importa?
Listo para validar lo que importa.
Plexicus es Proof-Driven AppSec: hallazgos validados, comprensión contextual y remediación revisada — anclada en evidencia, acotada contigo.