CWE-183 Base Borrador

Permissive List of Allowed Inputs

This vulnerability occurs when an application's security filter uses an allowlist that is too broad, mistakenly permitting dangerous inputs that should have been blocked. The flawed assumption that…

Definición

What is CWE-183?

This vulnerability occurs when an application's security filter uses an allowlist that is too broad, mistakenly permitting dangerous inputs that should have been blocked. The flawed assumption that everything on the list is safe creates a direct path for attackers to exploit the system.
An overly permissive allowlist is like a faulty bouncer at a club's door—it lets in troublemakers because the guest list isn't specific enough. Developers often create these lists to validate data like filenames, URLs, or user roles, but if the criteria are vague (e.g., allowing all files with a '.pdf' extension without checking the actual content), attackers can slip malicious payloads through. This bypasses the primary defense, leading to issues like command injection, path traversal, or cross-site scripting. Preventing this requires strict, context-aware validation rules that go beyond simple pattern matching. You must understand the exact, legitimate data your feature needs and deny everything else by default. Managing this at scale across hundreds of APIs and filters is difficult; an ASPM like Plexicus can help you track and remediate these flawed allowlist policies across your entire application stack, ensuring your validation logic is consistently robust.
Impacto en el mundo real

Real-world CVEs caused by CWE-183

  • CVE-2019-12799

    chain: bypass of untrusted deserialization issue (CWE-502) by using an assumed-trusted class (CWE-183)

  • CVE-2019-10458

    sandbox bypass using a method that is on an allowlist

  • CVE-2017-1000095

    sandbox bypass using unsafe methods that are on an allowlist

  • CVE-2019-10458

    CI/CD pipeline feature has unsafe elements in allowlist, allowing bypass of script restrictions

  • CVE-2017-1000095

    Default allowlist includes unsafe methods, allowing bypass of sandbox

Cómo lo explotan los atacantes

Ruta del atacante paso a paso

  1. 1

    Identifica una ruta de código que maneje entrada no confiable sin validación.

  2. 2

    Crea un payload que ejercite el comportamiento inseguro — inyección, traversal, overflow o abuso de lógica.

  3. 3

    Envía el payload a través de una solicitud normal y observa la reacción de la aplicación.

  4. 4

    Itera hasta que la respuesta filtre datos, ejecute código del atacante o escale privilegios.

Ejemplo de código vulnerable

Vulnerable pseudo

MITRE no ha publicado un ejemplo de código para esta CWE. El patrón siguiente es ilustrativo — consulta Recursos para referencias canónicas.

Vulnerable pseudo 
// Example pattern — see MITRE for the canonical references.
function handleRequest(input) {
  // Untrusted input flows directly into the sensitive sink.
  return executeUnsafe(input);
}
Ejemplo 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 prevención

How to prevent CWE-183

  • Architecture Use safe-by-default frameworks and APIs that prevent the unsafe pattern from being expressible.
  • Implementation Validate input at trust boundaries; use allowlists, not denylists.
  • Implementation Apply the principle of least privilege to credentials, file paths, and runtime permissions.
  • Testing Cover this weakness in CI: SAST rules + targeted unit tests for the data flow.
  • Operation Monitor logs for the runtime signals listed in the next section.
Señales de detección

How to detect CWE-183

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.)

Auto-corrección de Plexicus

Plexicus detecta automáticamente CWE-183 y abre un PR de corrección en menos de 60 segundos.

Codex Remedium escanea cada commit, identifica esta debilidad concreta y entrega un pull request listo para revisión con el parche. Sin tickets. Sin traspasos.

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Preguntas frecuentes

Frequently asked questions

¿Qué es CWE-183?

This vulnerability occurs when an application's security filter uses an allowlist that is too broad, mistakenly permitting dangerous inputs that should have been blocked. The flawed assumption that everything on the list is safe creates a direct path for attackers to exploit the system.

¿Qué gravedad tiene CWE-183?

MITRE no ha publicado una calificación de probabilidad de explotación para esta debilidad. Trátala como de impacto medio hasta que tu modelo de amenazas demuestre lo contrario.

¿Qué lenguajes o plataformas se ven afectados por CWE-183?

MITRE no ha especificado plataformas afectadas para esta CWE — puede aplicar a la mayoría de los stacks de aplicaciones.

¿Cómo puedo prevenir CWE-183?

Use safe-by-default frameworks, validate untrusted input at trust boundaries, and apply the principle of least privilege. Cover the data-flow signature in CI with SAST.

¿Cómo detecta y corrige Plexicus CWE-183?

El motor SAST de Plexicus detecta la firma de flujo de datos para CWE-183 en cada commit. Cuando hay coincidencia, nuestro agente Codex Remedium abre un PR de corrección con el código corregido, las pruebas y un resumen de una línea para el revisor.

¿Dónde puedo aprender más sobre CWE-183?

MITRE publica la definición canónica en https://cwe.mitre.org/data/definitions/183.html. También puedes consultar la documentación de OWASP y NIST para guías relacionadas.

Debilidades relacionadas

Weaknesses related to CWE-183

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Recursos

Further reading

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