CWE-493 Variante Brouillon High likelihood

Critical Public Variable Without Final Modifier

This vulnerability occurs when a security-sensitive variable is declared as public but not marked as final, allowing untrusted code to unexpectedly change its value after initialization.

Définition

What is CWE-493?

This vulnerability occurs when a security-sensitive variable is declared as public but not marked as final, allowing untrusted code to unexpectedly change its value after initialization.
When a critical variable—like a security flag, configuration setting, or cryptographic key—is made public without the `final` modifier, any part of the application with access to its class can alter its contents. This breaks the intended design and can lead to security failures, as other components may rely on that value remaining constant after being set. Manually tracking these exposed variables across a large codebase is challenging. An ASPM like Plexicus can automatically detect this pattern via SAST, and its AI remediation engine can suggest the specific code change—such as adding the `final` keyword or refactoring to a private field—saving significant manual review time and reducing risk.
Impact réel

Real-world CVEs caused by CWE-493

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. 1

    Suppose this WidgetData class is used for an e-commerce web site. The programmer attempts to prevent price-tampering attacks by setting the price of the widget using the constructor.

  2. 2

    The price field is not final. Even though the value is set by the constructor, it could be modified by anybody that has access to an instance of WidgetData.

  3. 3

    Assume the following code is intended to provide the location of a configuration file that controls execution of the application.

  4. 4

    While this field is readable from any function, and thus might allow an information leak of a pathname, a more serious problem is that it can be changed by any function.

Exemple de code vulnérable

Vulnerable Java

Suppose this WidgetData class is used for an e-commerce web site. The programmer attempts to prevent price-tampering attacks by setting the price of the widget using the constructor.

Vulnérable Java 
public final class WidgetData extends Applet {
  	public float price;
  	...
  	public WidgetData(...) {
  		this.price = LookupPrice("MyWidgetType");
  	}
  }
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-493

  • Implementation Declare all public fields as final when possible, especially if it is used to maintain internal state of an Applet or of classes used by an Applet. If a field must be public, then perform all appropriate sanity checks before accessing the field from your code.
Signaux de détection

How to detect CWE-493

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.)

Correction automatique Plexicus

Plexicus détecte automatiquement CWE-493 et ouvre une PR de correction en moins de 60 secondes.

Codex Remedium analyse chaque commit, identifie cette faiblesse précise et livre une pull request prête à être relue avec le correctif. Pas de tickets. Pas de transferts.

Obtenir une démo Essayer Plexicus gratuitement
Questions fréquentes

Frequently asked questions

Qu'est-ce que CWE-493 ?

This vulnerability occurs when a security-sensitive variable is declared as public but not marked as final, allowing untrusted code to unexpectedly change its value after initialization.

Quelle est la gravité de CWE-493 ?

MITRE évalue la probabilité d'exploitation comme Élevée — cette faiblesse est activement exploitée et doit être priorisée pour la remédiation.

Quels langages ou plateformes sont affectés par CWE-493 ?

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

Comment puis-je prévenir CWE-493 ?

Declare all public fields as final when possible, especially if it is used to maintain internal state of an Applet or of classes used by an Applet. If a field must be public, then perform all appropriate sanity checks before accessing the field from your code.

Comment Plexicus détecte et corrige CWE-493 ?

Le moteur SAST de Plexicus reconnaît la signature de flux de données de CWE-493 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-493 ?

MITRE publie la définition canonique à https://cwe.mitre.org/data/definitions/493.html. Vous pouvez également consulter la documentation OWASP et NIST pour des conseils adjacents.

Faiblesses associées

Weaknesses related to CWE-493

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Ressources

Further reading

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