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

Definição

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.

Impacto no mundo real

Real-world CVEs caused by CWE-496

Ainda não há referências CVE públicas associadas a este CWE no catálogo da MITRE.

Como os atacantes a exploram

Trajeto do atacante passo a passo

1
Identificar um caminho de código que trata input não confiável sem validação.
2
Criar um payload que explora o comportamento inseguro — injeção, traversal, overflow ou abuso de lógica.
3
Entregar o payload através de um pedido normal e observar a reação da aplicação.
4
Iterar até que a resposta exponha dados, execute código do atacante ou escale privilégios.

Exemplo de código vulnerável

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.

Vulnerável Java

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

Exemplo de código seguro

Secure pseudo

Seguro 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 verificação de prevenção

How to prevent CWE-496

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

Sinais de deteção

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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Perguntas frequentes

Frequently asked questions

O que é o 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.

Qual a gravidade do CWE-496?

A MITRE não publicou uma classificação de probabilidade de exploração para esta fraqueza. Trate-a como impacto médio até o seu modelo de ameaças provar o contrário.

Que linguagens ou plataformas são afetadas pelo CWE-496?

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

Como posso prevenir o CWE-496?

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

Como é que o Plexicus deteta e corrige o CWE-496?

O motor SAST do Plexicus correlaciona a assinatura de fluxo de dados do CWE-496 em cada commit. Quando é encontrada uma correspondência, o nosso agente Codex Remedium abre um PR de correção com o código corrigido, testes e um resumo de uma linha para o revisor.

Onde posso saber mais sobre o CWE-496?

A MITRE publica a definição canónica em https://cwe.mitre.org/data/definitions/496.html. Pode também consultar a documentação da OWASP e do NIST para orientações adjacentes.

Fraquezas relacionadas

Weaknesses related to CWE-496

CWE-664 Pai

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Public Data Assigned to Private Array-Typed Field

What is CWE-496?

Real-world CVEs caused by CWE-496

Trajeto do atacante passo a passo

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`