CWE-374 Base Borrador Medium likelihood

Passing Mutable Objects to an Untrusted Method

This vulnerability occurs when a function receives a direct reference to mutable data, such as an object or array, instead of a safe copy of that data.

Definición

What is CWE-374?

This vulnerability occurs when a function receives a direct reference to mutable data, such as an object or array, instead of a safe copy of that data.
When you pass a mutable object directly to a method—especially one from an external library or untrusted code—that method can alter or even delete the contents of your object. This breaks a fundamental assumption in your code: that the data you own remains under your control. The called function might change values, add unexpected elements, or clear the object entirely, leading to inconsistent states, crashes, or logic errors in your application. To prevent this, you should create and pass a defensive copy (a clone or deep copy) of the mutable data before sending it to any code you don't fully control. This ensures the original data remains intact and valid, regardless of what the external method does. Always treat mutable data passed across trust boundaries as potentially hostile and isolate it through copying.
Impacto en el mundo real

Real-world CVEs caused by CWE-374

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. 1

    The following example demonstrates the weakness.

  2. 2

    In this example, bar and baz will be passed by reference to doOtherStuff() which may change them.

  3. 3

    In the following Java example, the BookStore class manages the sale of books in a bookstore, this class includes the member objects for the bookstore inventory and sales database manager classes. The BookStore class includes a method for updating the sales database and inventory when a book is sold. This method retrieves a Book object from the bookstore inventory object using the supplied ISBN number for the book class, then calls a method for the sales object to update the sales information and then calls a method for the inventory object to update inventory for the BookStore.

  4. 4

    However, in this example the Book object that is retrieved and passed to the method of the sales object could have its contents modified by the method. This could cause unexpected results when the book object is sent to the method for the inventory object to update the inventory.

  5. 5

    In the Java programming language arguments to methods are passed by value, however in the case of objects a reference to the object is passed by value to the method. When an object reference is passed as a method argument a copy of the object reference is made within the method and therefore both references point to the same object. This allows the contents of the object to be modified by the method that holds the copy of the object reference. [REF-374]

Ejemplo de código vulnerable

Vulnerable C

The following example demonstrates the weakness.

Vulnerable C 
private:
  	int foo;
  	complexType bar;
  	String baz;
  	otherClass externalClass;
  public:
  	void doStuff() {
  		externalClass.doOtherStuff(foo, bar, baz)
  	}
Ejemplo de código seguro

Secure Java

To prevent the contents of the Book object from being modified, a copy of the Book object should be made before the method call to the sales object. In the following example a copy of the Book object is made using the clone() method and the copy of the Book object is passed to the method of the sales object. This will prevent any changes being made to the original Book object.

Seguro Java 
...
  public void updateSalesAndInventoryForBookSold(String bookISBN) {
```
// Get book object from inventory using ISBN* 
  		Book book = inventory.getBookWithISBN(bookISBN);
  		
  		 *// Create copy of book object to make sure contents are not changed* 
  		Book bookSold = (Book) book.clone();
  		
  		 *// update sales information for book sold* 
  		sales.updateSalesInformation(bookSold);
  		
  		 *// update inventory* 
  		inventory.updateInventory(book);}
  ...
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-374

  • Implementation Pass in data which should not be altered as constant or immutable.
  • Implementation Clone all mutable data before passing it into an external function . This is the preferred mitigation. This way, regardless of what changes are made to the data, a valid copy is retained for use by the class.
Señales de detección

How to detect CWE-374

SAST High

Ejecuta análisis estático (SAST) sobre el código buscando el patrón inseguro en el flujo de datos.

DAST Moderate

Ejecuta pruebas dinámicas de seguridad de aplicaciones (DAST) contra el endpoint en vivo.

Runtime Moderate

Vigila los logs en tiempo de ejecución para detectar trazas de excepción inusuales, entradas malformadas o intentos de bypass de autorización.

Code review Moderate

Revisión de código: marca cualquier código nuevo que maneje entrada desde esta superficie sin usar los helpers validados del framework.

Auto-corrección de Plexicus

Plexicus detecta automáticamente CWE-374 y abre un PR de corrección en menos de 60 segundos.

Codex Remedium escanea cada commit, identifica esta debilidad concreta y entrega un pull request listo para revisión con el parche. Sin tickets. Sin traspasos.

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Preguntas frecuentes

Frequently asked questions

¿Qué es CWE-374?

This vulnerability occurs when a function receives a direct reference to mutable data, such as an object or array, instead of a safe copy of that data.

¿Qué gravedad tiene CWE-374?

MITRE califica la probabilidad de explotación como Media — la explotación es realista pero suele requerir condiciones específicas.

¿Qué lenguajes o plataformas se ven afectados por CWE-374?

MITRE lists the following affected platforms: C, C++, Java, C#.

¿Cómo puedo prevenir CWE-374?

Pass in data which should not be altered as constant or immutable. Clone all mutable data before passing it into an external function . This is the preferred mitigation. This way, regardless of what changes are made to the data, a valid copy is retained for use by the class.

¿Cómo detecta y corrige Plexicus CWE-374?

El motor SAST de Plexicus detecta la firma de flujo de datos para CWE-374 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-374?

MITRE publica la definición canónica en https://cwe.mitre.org/data/definitions/374.html. También puedes consultar la documentación de OWASP y NIST para guías relacionadas.

Debilidades relacionadas

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Recursos

Further reading

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