CWE-495: Private Data Structure Returned From A Public Method

Définition

What is CWE-495?

This vulnerability occurs when a public method directly returns a reference to a private, internal data structure. Because the reference is live, external callers can bypass intended controls and modify the data unexpectedly, corrupting the application's state.

This flaw breaks a core principle of encapsulation in object-oriented design. The private data structure—like an array, collection, or object—is meant to be managed solely by the class's own methods. By handing out a direct reference, you allow external code to add, remove, or alter elements without validation, leading to data corruption, security bypasses, or crashes that are difficult to debug. The fix is to return either a copy of the data (defensive copying) or an immutable view, ensuring the internal state remains protected. Identifying every instance of this pattern across a large codebase can be tedious. While SAST tools can flag the risky return statements, Plexicus uses AI to analyze the context and automatically suggest the correct remediation—such as implementing `Collections.unmodifiableList()` in Java or a slice copy in Go—saving developers hours of manual refactoring and ensuring consistent fixes.

Impact réel

Real-world CVEs caused by CWE-495

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

Here, a public method in a Java class returns a reference to a private array. Given that arrays in Java are mutable, any modifications made to the returned reference would be reflected in the original private array.

Vulnérable Java

private String[] colors;
  public String[] getColors() {
  	return colors;
  }

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-495

Implementation Declare the method private.
Implementation Clone the member data and keep an unmodified version of the data private to the object.
Implementation Use public setter methods that govern how a private member can be modified.

Signaux de détection

How to detect CWE-495

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-495

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.

Request AI Swarm Pentest

Questions fréquentes

Frequently asked questions

Qu'est-ce que CWE-495 ?

This vulnerability occurs when a public method directly returns a reference to a private, internal data structure. Because the reference is live, external callers can bypass intended controls and modify the data unexpectedly, corrupting the application's state.

Quelle est la gravité de CWE-495 ?

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-495 ?

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

Comment puis-je prévenir CWE-495 ?

Declare the method private. Clone the member data and keep an unmodified version of the data private to the object.

Comment Plexicus détecte et corrige CWE-495 ?

Le moteur SAST de Plexicus reconnaît la signature de flux de données de CWE-495 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-495 ?

MITRE publie la définition canonique à https://cwe.mitre.org/data/definitions/495.html. Vous pouvez également consulter la documentation OWASP et NIST pour des conseils adjacents.

Faiblesses associées

Weaknesses related to CWE-495

CWE-664 Parent

Prêt à valider ce qui compte.

Plexicus est Proof-Driven AppSec : findings validés, compréhension contextuelle et remédiation relue — ancrée dans la preuve, scopée avec vous.

Réserver un Pentest

Private Data Structure Returned From A Public Method

What is CWE-495?

Real-world CVEs caused by CWE-495

Parcours de l'attaquant étape par étape

Vulnerable Java

Secure pseudo

How to prevent CWE-495

How to detect CWE-495

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

Frequently asked questions

Weaknesses related to CWE-495

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

Prêt à valider ce qui compte.

Vérifiez si l'AI Swarm Pentest convient à votre environnement.

Demande reçue. Réservez la prochaine étape.

Sample evidence handover

Server-Side Request Forgery in `webhooks/receiver`