CWE-496: Public Data Assigned to Private Array-Typed Field

Définition

What is CWE-496?

This vulnerability occurs when a developer stores sensitive data in a private array, but then assigns a publicly accessible reference to that same array. This effectively makes all the private array's contents available to unauthorized code, bypassing intended access controls.

When you declare an array field as `private`, you're telling the system that external code shouldn't directly access it. However, if you then assign a public variable or return value to point to that same private array, you've created a backdoor. Any code with access to the public reference can now read, modify, or delete the supposedly private data, completely undermining your encapsulation. To prevent this, never expose references to your private arrays. Instead, return copies (defensive copies) of the array data or use immutable collections. Always validate that your getter methods or public fields don't provide direct access to mutable private objects, as this is a common oversight that leads to serious data exposure.

Impact réel

Real-world CVEs caused by CWE-496

Aucune référence CVE publique n'est liée à ce CWE dans le catalogue MITRE pour le moment.

Comment les attaquants l'exploitent

Parcours de l'attaquant étape par étape

1
Identifier un chemin de code qui traite des entrées non fiables sans validation.
2
Élaborer une charge utile qui exploite le comportement non sécurisé — injection, traversal, débordement ou abus de logique.
3
Délivrer la charge utile via une requête normale et observer la réaction de l'application.
4
Itérer jusqu'à ce que la réponse divulgue des données, exécute le code de l'attaquant ou élève les privilèges.

Exemple de code vulnérable

Vulnerable Java

In the example below, the setRoles() method assigns a publically-controllable array to a private field, thus allowing the caller to modify the private array directly by virtue of the fact that arrays in Java are mutable.

Vulnérable Java

private String[] userRoles;
  public void setUserRoles(String[] userRoles) {
  	this.userRoles = userRoles;
  }

Exemple de code sécurisé

Secure pseudo

Sécurisé 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.

Liste de contrôle de prévention

How to prevent CWE-496

Implementation Do not allow objects to modify private members of a class.

Signaux de détection

How to detect CWE-496

Automated Static Analysis High

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-496

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Questions fréquentes

Frequently asked questions

Qu'est-ce que CWE-496 ?

This vulnerability occurs when a developer stores sensitive data in a private array, but then assigns a publicly accessible reference to that same array. This effectively makes all the private array's contents available to unauthorized code, bypassing intended access controls.

Quelle est la gravité de CWE-496 ?

MITRE n'a pas publié de note de probabilité d'exploitation pour cette faiblesse. Traitez-la comme un impact moyen jusqu'à ce que votre modèle de menace prouve le contraire.

Quels langages ou plateformes sont affectés par CWE-496 ?

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

Comment puis-je prévenir CWE-496 ?

Do not allow objects to modify private members of a class.

Comment Plexicus détecte et corrige CWE-496 ?

Le moteur SAST de Plexicus reconnaît la signature de flux de données de CWE-496 à chaque commit. Lorsqu'une correspondance est trouvée, notre agent Codex Remedium ouvre une PR de correction avec le code corrigé, les tests et un résumé d'une ligne pour le relecteur.

Où puis-je en savoir plus sur CWE-496 ?

MITRE publie la définition canonique à https://cwe.mitre.org/data/definitions/496.html. Vous pouvez également consulter la documentation OWASP et NIST pour des conseils adjacents.

Faiblesses associées

Weaknesses related to CWE-496

CWE-664 Parent

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Public Data Assigned to Private Array-Typed Field

What is CWE-496?

Real-world CVEs caused by CWE-496

Parcours de l'attaquant étape par étape

Vulnerable Java

Secure pseudo

How to prevent CWE-496

How to detect CWE-496

Don't catalog this weakness. Prove it's reachable.

Frequently asked questions

Weaknesses related to CWE-496

Improper Control of a Resource Through its Lifetime

Incorrect Access of Indexable Resource ('Range Error')

Creation of Emergent Resource

Improper Preservation of Consistency Between Independent Representations of Shared State

Reliance on Component That is Not Updateable

Information Loss or Omission

Incomplete Internal State Distinction

Uncontrolled Resource Consumption

Improper Resource Shutdown or Release

Further reading

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Sample evidence handover

Server-Side Request Forgery in `webhooks/receiver`