CWE-407 Classe Incomplet 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…

Définition

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.
Impact réel

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.

Comment les attaquants l'exploitent

Parcours de l'attaquant étape par étape

  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.

Exemple de code vulnérable

Vulnerable JavaScript

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

Vulnérable JavaScript 
var test_string = "Bad characters: $@#";
 var bad_pattern = /^(\w+\s?)*$/i;
 var result = test_string.search(bad_pattern);
Exemple de code sécurisé

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:

Sécurisé 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.
Liste de contrôle de prévention

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.
Signaux de détection

How to detect CWE-407

SAST High

Exécuter une analyse statique (SAST) sur le code source à la recherche du motif non sécurisé dans le flux de données.

DAST Moderate

Exécuter des tests de sécurité applicative dynamique (DAST) contre le point de terminaison en ligne.

Runtime Moderate

Surveiller les journaux runtime pour détecter des traces d'exception inhabituelles, des entrées malformées ou des tentatives de contournement d'autorisation.

Code review Moderate

Revue de code : signaler tout nouveau code qui traite les entrées de cette surface sans utiliser les helpers du framework validés.

Correction automatique Plexicus

Plexicus détecte automatiquement CWE-407 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-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.

Quelle est la gravité de CWE-407 ?

MITRE évalue la probabilité d'exploitation comme Faible — l'exploitation est rare, mais la faiblesse doit tout de même être corrigée lorsqu'elle est découverte.

Quels langages ou plateformes sont affectés par CWE-407 ?

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-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.

Comment Plexicus détecte et corrige CWE-407 ?

Le moteur SAST de Plexicus reconnaît la signature de flux de données de CWE-407 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-407 ?

MITRE publie la définition canonique à https://cwe.mitre.org/data/definitions/407.html. Vous pouvez également consulter la documentation OWASP et NIST pour des conseils adjacents.

Faiblesses associées

Weaknesses related to CWE-407

CWE-405 Parent

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 Frère

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 Frère

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 Frère

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 Frère

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 Frère

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 Frère

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 Frère

Inefficient CPU Computation

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

CWE-406 Frère

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,…

Ressources

Further reading

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