CWE-201 Base Brouillon

Insertion of Sensitive Information Into Sent Data

This vulnerability occurs when an application sends data to an external party, but accidentally includes sensitive information—like passwords, keys, or personal data—that the recipient should not be…

Définition

What is CWE-201?

This flaw often happens because of overly broad data selection or logging mechanisms that package more information than necessary for a given transaction. For example, an API response might return an entire user object, including internal fields like hashed passwords or security questions, instead of just the needed profile data. Developers should carefully review all data payloads sent to clients, third-party services, or logs, ensuring they follow the principle of least privilege and expose only what is explicitly required. Catching these leaks manually is challenging, as sensitive data can be buried deep in nested objects or only appear under specific conditions. While SAST tools can flag patterns of data exposure, Plexicus uses AI to analyze data flows in context and suggest precise code fixes—such as implementing stricter output filters or using data sanitization libraries—saving hours of manual review and reducing the risk of accidental disclosure across your entire application stack.

Vulnerability Diagram CWE-201

Impact réel

Real-world CVEs caused by CWE-201

CVE-2022-0708

Collaboration platform does not clear team emails in a response, allowing leak of email addresses

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 SQL

The following is an actual MySQL error statement:

Vulnérable SQL

Warning: mysql_pconnect(): Access denied for user: 'root@localhost' (Using password: N1nj4) in /usr/local/www/wi-data/includes/database.inc on line 4

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-201

Requirements Specify which data in the software should be regarded as sensitive. Consider which types of users should have access to which types of data.
Implementation Ensure that any possibly sensitive data specified in the requirements is verified with designers to ensure that it is either a calculated risk or mitigated elsewhere. Any information that is not necessary to the functionality should be removed in order to lower both the overhead and the possibility of security sensitive data being sent.
System Configuration Setup default error messages so that unexpected errors do not disclose sensitive information.
Architecture and Design Compartmentalize the system to have "safe" areas where trust boundaries can be unambiguously drawn. Do not allow sensitive data to go outside of the trust boundary and always be careful when interfacing with a compartment outside of the safe area. Ensure that appropriate compartmentalization is built into the system design, and the compartmentalization allows for and reinforces privilege separation functionality. Architects and designers should rely on the principle of least privilege to decide the appropriate time to use privileges and the time to drop privileges.

Signaux de détection

How to detect CWE-201

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-201 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-201 ?

Quelle est la gravité de CWE-201 ?

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-201 ?

MITRE n'a pas spécifié les plateformes affectées pour ce CWE — il peut s'appliquer à la plupart des stacks applicatives.

Comment puis-je prévenir CWE-201 ?

Specify which data in the software should be regarded as sensitive. Consider which types of users should have access to which types of data. Ensure that any possibly sensitive data specified in the requirements is verified with designers to ensure that it is either a calculated risk or mitigated elsewhere. Any information that is not necessary to the functionality should be removed in order to lower both the overhead and the possibility of security sensitive data being sent.

Comment Plexicus détecte et corrige CWE-201 ?

Le moteur SAST de Plexicus reconnaît la signature de flux de données de CWE-201 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-201 ?

MITRE publie la définition canonique à https://cwe.mitre.org/data/definitions/201.html. Vous pouvez également consulter la documentation OWASP et NIST pour des conseils adjacents.

Faiblesses associées

Weaknesses related to CWE-201

CWE-200 Parent

Exposure of Sensitive Information to an Unauthorized Actor

This weakness occurs when an application unintentionally reveals sensitive data to someone who shouldn't have access to it.

CWE-1258 Frère

Exposure of Sensitive System Information Due to Uncleared Debug Information

This vulnerability occurs when hardware fails to erase sensitive data like cryptographic keys and intermediate values before entering…

CWE-1273 Frère

Device Unlock Credential Sharing

This vulnerability occurs when the secret keys or passwords required to unlock a device's hidden features are shared between multiple…

CWE-1295 Frère

Debug Messages Revealing Unnecessary Information

The product's debug messages or logs expose excessive internal system details, potentially revealing sensitive information that could aid…

CWE-1431 Frère

Driving Intermediate Cryptographic State/Results to Hardware Module Outputs

This vulnerability occurs when a hardware cryptographic module leaks sensitive internal data through its output channels. Instead of only…

CWE-203 Frère

Observable Discrepancy

This vulnerability occurs when an application responds differently to unauthorized users based on internal conditions. Attackers can…

CWE-209 Frère

Generation of Error Message Containing Sensitive Information

This vulnerability occurs when an application reveals sensitive details about its internal systems, user data, or environment within error…

CWE-213 Frère

Exposure of Sensitive Information Due to Incompatible Policies

This vulnerability occurs when a system's data handling aligns with the developer's security rules but accidentally reveals information…

CWE-215 Frère

Insertion of Sensitive Information Into Debugging Code

This vulnerability occurs when developers embed sensitive data, such as passwords or API keys, within debugging statements like logs or…

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