Ejecuta análisis estático (SAST) sobre el código buscando el patrón inseguro en el flujo de datos.
CWE-407 Clase Incompleto
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
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C++ library for image metadata has "quadratic complexity" issue with unnecessarily repetitive parsing each time an invalid character is encountered
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Python has "quadratic complexity" issue when converting string to int with many digits in unexpected bases
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server allows ReDOS with crafted User-Agent strings, due to overlapping capture groups that cause excessive backtracking.
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Perl-based email address parser has "quadratic complexity" issue via a string that does not contain a valid address
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CPU consumption via inputs that cause many hash table collisions.
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CPU consumption via inputs that cause many hash table collisions.
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Product performs unnecessary processing before dropping an invalid packet.
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CPU and memory consumption using many wildcards.
Cómo lo explotan los atacantes
Ruta del atacante paso a paso
- 1
This example attempts to check if an input string is a "sentence" [REF-1164].
- 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
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].
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:
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
Ejecuta pruebas dinámicas de seguridad de aplicaciones (DAST) contra el endpoint en vivo.
Vigila los logs en tiempo de ejecución para detectar trazas de excepción inusuales, entradas malformadas o intentos de bypass de autorización.
Revisión de código: marca cualquier código nuevo que maneje entrada desde esta superficie sin usar los helpers validados del framework.
CWE-407
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.
Preguntas frecuentes ¿Qué es CWE-407?
¿Qué gravedad tiene CWE-407?
¿Qué lenguajes o plataformas se ven afectados por CWE-407?
¿Cómo puedo prevenir CWE-407?
¿Cómo detecta y corrige Plexicus CWE-407?
¿Dónde puedo aprender más sobre CWE-407?
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
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Invokable Control Element with Excessive File or Data Access Operations
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Excessive Index Range Scan for a Data Resource
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Inefficient CPU Computation
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CWE-406 Hermano
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Listo para validar lo que importa.
Plexicus es Proof-Driven AppSec: hallazgos validados, comprensión contextual y remediación revisada — anclada en evidencia, acotada contigo.