CWE-407 Clase Incompleto Low likelihood

Inefficient Algorithmic Complexity

This vulnerability occurs when a software component uses an algorithm with poor worst-case performance. An attacker can exploit this by providing specially crafted input that forces the algorithm…

Definición

What is CWE-407?

This vulnerability occurs when a software component uses an algorithm with poor worst-case performance. An attacker can exploit this by providing specially crafted input that forces the algorithm into its slowest possible execution path, leading to severe performance degradation or denial of service.
At its core, this issue is about predictable resource exhaustion. Common examples include using algorithms with quadratic (O(n²)) or exponential complexity for tasks that handle user-controlled data size, like inefficient sorting or search algorithms on large, attacker-supplied inputs. When exploited, this can cause excessive CPU consumption, memory usage, or runtime delays, crippling the application's availability. Developers can mitigate this by selecting algorithms with consistent, efficient complexity (like O(n log n) for sorting) and implementing safeguards. These include setting hard limits on input size, using timeouts for operations, and switching to more performant algorithms or data structures when processing thresholds are crossed. Always profile code with worst-case input scenarios during testing.
Impacto en el mundo real

Real-world CVEs caused by CWE-407

  • CVE-2021-32617

    C++ library for image metadata has "quadratic complexity" issue with unnecessarily repetitive parsing each time an invalid character is encountered

  • CVE-2020-10735

    Python has "quadratic complexity" issue when converting string to int with many digits in unexpected bases

  • CVE-2020-5243

    server allows ReDOS with crafted User-Agent strings, due to overlapping capture groups that cause excessive backtracking.

  • CVE-2014-1474

    Perl-based email address parser has "quadratic complexity" issue via a string that does not contain a valid address

  • CVE-2003-0244

    CPU consumption via inputs that cause many hash table collisions.

  • CVE-2003-0364

    CPU consumption via inputs that cause many hash table collisions.

  • CVE-2002-1203

    Product performs unnecessary processing before dropping an invalid packet.

  • CVE-2001-1501

    CPU and memory consumption using many wildcards.

Cómo lo explotan los atacantes

Ruta del atacante paso a paso

  1. 1

    This example attempts to check if an input string is a "sentence" [REF-1164].

  2. 2

    The regular expression has a vulnerable backtracking clause inside (\w+\s?)*$ which can be triggered to cause a Denial of Service by processing particular phrases. To fix the backtracking problem, backtracking is removed with the ?= portion of the expression which changes it to a lookahead and the \2 which prevents the backtracking. The modified example is:

  3. 3

    Note that [REF-1164] has a more thorough (and lengthy) explanation of everything going on within the RegEx.

Ejemplo de código vulnerable

Vulnerable JavaScript

This example attempts to check if an input string is a "sentence" [REF-1164].

Vulnerable JavaScript 
var test_string = "Bad characters: $@#";
 var bad_pattern = /^(\w+\s?)*$/i;
 var result = test_string.search(bad_pattern);
Ejemplo de código seguro

Secure JavaScript

The regular expression has a vulnerable backtracking clause inside (\w+\s?)*$ which can be triggered to cause a Denial of Service by processing particular phrases. To fix the backtracking problem, backtracking is removed with the ?= portion of the expression which changes it to a lookahead and the \2 which prevents the backtracking. The modified example is:

Seguro JavaScript 
var test_string = "Bad characters: $@#";
 var good_pattern = /^((?=(\w+))\2\s?)*$/i;
 var result = test_string.search(good_pattern);
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-407

  • 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-407

SAST High

Ejecuta análisis estático (SAST) sobre el código buscando el patrón inseguro en el flujo de datos.

DAST Moderate

Ejecuta pruebas dinámicas de seguridad de aplicaciones (DAST) contra el endpoint en vivo.

Runtime Moderate

Vigila los logs en tiempo de ejecución para detectar trazas de excepción inusuales, entradas malformadas o intentos de bypass de autorización.

Code review Moderate

Revisión de código: marca cualquier código nuevo que maneje entrada desde esta superficie sin usar los helpers validados del framework.

Auto-corrección de Plexicus

Plexicus detecta automáticamente CWE-407 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.

Solicitar demo Probar Plexicus gratis
Preguntas frecuentes

Frequently asked questions

¿Qué es CWE-407?

This vulnerability occurs when a software component uses an algorithm with poor worst-case performance. An attacker can exploit this by providing specially crafted input that forces the algorithm into its slowest possible execution path, leading to severe performance degradation or denial of service.

¿Qué gravedad tiene CWE-407?

MITRE califica la probabilidad de explotación como Baja — la explotación es poco frecuente, pero la debilidad debe corregirse cuando se descubra.

¿Qué lenguajes o plataformas se ven afectados por CWE-407?

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

¿Cómo puedo prevenir CWE-407?

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-407?

El motor SAST de Plexicus detecta la firma de flujo de datos para CWE-407 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-407?

MITRE publica la definición canónica en https://cwe.mitre.org/data/definitions/407.html. También puedes consultar la documentación de OWASP y NIST para guías relacionadas.

Debilidades relacionadas

Weaknesses related to CWE-407

CWE-405 Padre

Asymmetric Resource Consumption (Amplification)

This vulnerability occurs when a system allows an attacker to trigger a disproportionate amount of resource consumption—like CPU, memory,…

CWE-1050 Hermano

Excessive Platform Resource Consumption within a Loop

This vulnerability occurs when a loop contains code that repeatedly consumes critical system resources like file handles, database…

CWE-1072 Hermano

Data Resource Access without Use of Connection Pooling

This weakness occurs when an application creates a new database connection for every request instead of using a managed connection pool.…

CWE-1073 Hermano

Non-SQL Invokable Control Element with Excessive Number of Data Resource Accesses

This weakness occurs when a client-side function or method makes an excessive number of individual data requests through a non-SQL data…

CWE-1084 Hermano

Invokable Control Element with Excessive File or Data Access Operations

This weakness occurs when a single function or method performs an excessive number of file or database operations, such as repeated reads,…

CWE-1089 Hermano

Large Data Table with Excessive Number of Indices

This weakness occurs when an application uses a database table with a very large number of rows and creates too many indexes on it,…

CWE-1094 Hermano

Excessive Index Range Scan for a Data Resource

This weakness occurs when a database query performs an index range scan that can access an unnecessarily large number of rows from a…

CWE-1176 Hermano

Inefficient CPU Computation

This weakness occurs when software uses inefficient algorithms or suboptimal CPU operations, performing unnecessary or overly complex…

CWE-406 Hermano

Insufficient Control of Network Message Volume (Network Amplification)

This vulnerability occurs when a system fails to properly limit the amount of network traffic it can generate in response to a request,…

Recursos

Further reading

Listo cuando tú lo estés

Deja de pagar por desarrollador.
Empieza a cerrar el bucle.

Plexicus es el ASPM nativo de IA que escanea, filtra, corrige, pentestea y explica — de forma autónoma. Desarrolladores ilimitados, repos ilimitados, acciones de IA de uso justo. Nivel gratuito real, €269/mo anual cuando estés listo.

Comenzar gratis Reservar una demo