Ejecuta análisis estático (SAST) sobre el código buscando el patrón inseguro en el flujo de datos.
CWE-543 Variante Incompleto
Use of Singleton Pattern Without Synchronization in a Multithreaded Context
This vulnerability occurs when a singleton pattern is implemented in a multithreaded application without proper synchronization, potentially leading to multiple instances or corrupted state.
Definición
What is CWE-543?
This vulnerability occurs when a singleton pattern is implemented in a multithreaded application without proper synchronization, potentially leading to multiple instances or corrupted state.
The singleton pattern is designed to ensure only one instance of a class exists. However, in a multithreaded environment, if the creation of that instance is not properly synchronized, multiple threads can simultaneously pass the instance check and create their own copies. This breaks the fundamental guarantee of the pattern and leads to unpredictable application behavior.
To prevent this, developers must implement thread-safe initialization. Common solutions include using synchronized blocks during creation, employing eager initialization at class-load time, or leveraging language-specific constructs like atomic references or initialization-on-demand holder idioms. The correct approach depends on your performance requirements and programming language, but ignoring synchronization is not an option in concurrent code.
Impacto en el mundo real
Real-world CVEs caused by CWE-543
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
This method is part of a singleton pattern, yet the following singleton() pattern is not thread-safe. It is possible that the method will create two objects instead of only one.
- 2
Consider the following course of events:
- 3
- Thread A enters the method, finds singleton to be null, begins the NumberConverter constructor, and then is swapped out of execution. - Thread B enters the method and finds that singleton remains null. This will happen if A was swapped out during the middle of the constructor, because the object reference is not set to point at the new object on the heap until the object is fully initialized. - Thread B continues and constructs another NumberConverter object and returns it while exiting the method. - Thread A continues, finishes constructing its NumberConverter object, and returns its version.
- 4
At this point, the threads have created and returned two different objects.
Ejemplo de código vulnerable
Vulnerable Java
This method is part of a singleton pattern, yet the following singleton() pattern is not thread-safe. It is possible that the method will create two objects instead of only one.
private static NumberConverter singleton;
public static NumberConverter get_singleton() {
if (singleton == null) {
singleton = new NumberConverter();
}
return singleton;
} Ejemplo de código seguro
Secure pseudo
// Validate, sanitize, or use a safe API before reaching the sink.
function handleRequest(input) {
const safe = validateAndEscape(input);
return executeWithGuards(safe);
} 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-543
- Architecture and Design Use the Thread-Specific Storage Pattern. See References.
- Implementation Do not use member fields to store information in the Servlet. In multithreading environments, storing user data in Servlet member fields introduces a data access race condition.
- Implementation Avoid using the double-checked locking pattern in language versions that cannot guarantee thread safety. This pattern may be used to avoid the overhead of a synchronized call, but in certain versions of Java (for example), this has been shown to be unsafe because it still introduces a race condition (CWE-209).
Señales de detección
How to detect CWE-543
Ejecuta pruebas dinámicas de seguridad de aplicaciones (DAST) contra el endpoint en vivo.
Vigila los logs en tiempo de ejecución para detectar trazas de excepción inusuales, entradas malformadas o intentos de bypass de autorización.
Revisión de código: marca cualquier código nuevo que maneje entrada desde esta superficie sin usar los helpers validados del framework.
CWE-543
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-543?
¿Qué gravedad tiene CWE-543?
¿Qué lenguajes o plataformas se ven afectados por CWE-543?
¿Cómo puedo prevenir CWE-543?
¿Cómo detecta y corrige Plexicus CWE-543?
¿Dónde puedo aprender más sobre CWE-543?
Frequently asked questions
¿Qué es CWE-543?
This vulnerability occurs when a singleton pattern is implemented in a multithreaded application without proper synchronization, potentially leading to multiple instances or corrupted state.
¿Qué gravedad tiene CWE-543?
MITRE no ha publicado una calificación de probabilidad de explotación para esta debilidad. Trátala como de impacto medio hasta que tu modelo de amenazas demuestre lo contrario.
¿Qué lenguajes o plataformas se ven afectados por CWE-543?
MITRE lists the following affected platforms: Java, C++.
¿Cómo puedo prevenir CWE-543?
Use the Thread-Specific Storage Pattern. See References. Do not use member fields to store information in the Servlet. In multithreading environments, storing user data in Servlet member fields introduces a data access race condition.
¿Cómo detecta y corrige Plexicus CWE-543?
El motor SAST de Plexicus detecta la firma de flujo de datos para CWE-543 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-543?
MITRE publica la definición canónica en https://cwe.mitre.org/data/definitions/543.html. También puedes consultar la documentación de OWASP y NIST para guías relacionadas.
Debilidades relacionadas
Weaknesses related to CWE-543
CWE-820 Padre
Missing Synchronization
This vulnerability occurs when multiple parts of your application (like threads or processes) use the same resource—such as a variable,…
CWE-1096 Hermano
Singleton Class Instance Creation without Proper Locking or Synchronization
This flaw occurs when a Singleton class is implemented without proper thread-safe controls, allowing multiple instances to be created in…
CWE-567 Hermano
Unsynchronized Access to Shared Data in a Multithreaded Context
This vulnerability occurs when multiple threads in an application can read and modify shared data, like static variables, without proper…
¿Listo para validar lo que importa?
Listo para validar lo que importa.
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