CWE-1265 Base Brouillon

Unintended Reentrant Invocation of Non-reentrant Code Via Nested Calls

This vulnerability occurs when a non-reentrant function is called, and during its execution, another call is triggered that unexpectedly re-enters the same non-reentrant code path, corrupting its…

Définition

What is CWE-1265?

This vulnerability occurs when a non-reentrant function is called, and during its execution, another call is triggered that unexpectedly re-enters the same non-reentrant code path, corrupting its internal state.

In complex software, a single function call can branch into many unexpected execution paths, especially when processing external inputs. Attackers can often manipulate these inputs—like scripts in a web browser or embedded code in a PDF—to force the program into a state where a nested call re-enters code that wasn't designed to handle re-invocation. This is dangerous because the non-reentrant code typically relies on global or static data that gets corrupted when called again before the first invocation finishes. For developers, the core issue is that a function assumes its own internal state or global resources remain stable for the duration of its execution. When a nested call—perhaps via a callback, event handler, or virtual method—breaks that assumption, it leads to race conditions, data corruption, or crashes. To prevent this, you must audit code paths triggered during non-reentrant operations and isolate or protect any state that shouldn't be accessed concurrently, even from within the same thread.

Impact réel

Real-world CVEs caused by CWE-1265

CVE-2014-1772

In this vulnerability, by registering a malicious onerror handler, an adversary can produce unexpected re-entrance of a CDOMRange object. [REF-1098]
CVE-2018-8174

This CVE covers several vulnerable scenarios enabled by abuse of the Class_Terminate feature in Microsoft VBScript. In one scenario, Class_Terminate is used to produce an undesirable re-entrance of ScriptingDictionary during execution of that object's destructor. In another scenario, a vulnerable condition results from a recursive entrance of a property setter method. This recursive invocation produces a second, spurious call to the Release method of a reference-counted object, causing a UAF when that object is freed prematurely. This vulnerability pattern has been popularized as "Double Kill". [REF-1099]

Comment les attaquants l'exploitent

Parcours de l'attaquant étape par étape

1
The implementation of the Widget class in the following C++ code is an example of code that is not designed to be reentrant. If an invocation of a method of Widget inadvertently produces a second nested invocation of a method of Widget, then data member backgroundImage may unexpectedly change during execution of the outer call.
2
Looking closer at this example, Widget::click() calls backgroundImage->click(), which in turn calls scriptEngine->fireOnImageClick(). The code within fireOnImageClick() invokes the appropriate script handler routine as defined by the document being rendered. In this scenario this script routine is supplied by an adversary and this malicious script makes a call to Widget::changeBackgroundImage(), deleting the Image object pointed to by backgroundImage. When control returns to Image::click, the function's backgroundImage "this" pointer (which is the former value of backgroundImage) is a dangling pointer. The root of this weakness is that while one operation on Widget (click) is in the midst of executing, a second operation on the Widget object may be invoked (in this case, the second invocation is a call to different method, namely changeBackgroundImage) that modifies the non-local variable.
3
This is another example of C++ code that is not designed to be reentrant.
4
The expected order of operations is a call to Request::setup(), followed by a call to Request::send(). Request::send() calls scriptEngine->coerceToString(_data) to coerce a script-provided parameter into a string. This operation may produce script execution. For example, if the script language is ECMAScript, arbitrary script execution may result if _data is an adversary-supplied ECMAScript object having a custom toString method. If the adversary's script makes a new call to Request::setup, then when control returns to Request::send, the field uri and the local variable credentials will no longer be consistent with one another. As a result, credentials for one resource will be shared improperly with a different resource. The root of this weakness is that while one operation on Request (send) is in the midst of executing, a second operation may be invoked (setup).

Exemple de code vulnérable

Vulnerable C++

The implementation of the Widget class in the following C++ code is an example of code that is not designed to be reentrant. If an invocation of a method of Widget inadvertently produces a second nested invocation of a method of Widget, then data member backgroundImage may unexpectedly change during execution of the outer call.

Vulnérable C++

class Widget
  {
  	private:
  		Image* backgroundImage;
  	public:
  		void click()
  		{
  			if (backgroundImage)
  			{
  				backgroundImage->click();
  			}
  		}
  		void changeBackgroundImage(Image* newImage)
  		{
  			if (backgroundImage)
  			{
  				delete backgroundImage;
  			}
  			backgroundImage = newImage;
  		}
  }
  class Image
  {
  	public:
  		void click()
  		{
  			scriptEngine->fireOnImageClick();
  			/* perform some operations using "this" pointer */
  		}
  }

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-1265

Architecture and Design When architecting a system that will execute untrusted code in response to events, consider executing the untrusted event handlers asynchronously (asynchronous message passing) as opposed to executing them synchronously at the time each event fires. The untrusted code should execute at the start of the next iteration of the thread's message loop. In this way, calls into non-reentrant code are strictly serialized, so that each operation completes fully before the next operation begins. Special attention must be paid to all places where type coercion may result in script execution. Performing all needed coercions at the very beginning of an operation can help reduce the chance of operations executing at unexpected junctures.
Implementation Make sure the code (e.g., function or class) in question is reentrant by not leveraging non-local data, not modifying its own code, and not calling other non-reentrant code.

Signaux de détection

How to detect CWE-1265

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-1265 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-1265 ?

Quelle est la gravité de CWE-1265 ?

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-1265 ?

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-1265 ?

When architecting a system that will execute untrusted code in response to events, consider executing the untrusted event handlers asynchronously (asynchronous message passing) as opposed to executing them synchronously at the time each event fires. The untrusted code should execute at the start of the next iteration of the thread's message loop. In this way, calls into non-reentrant code are strictly serialized, so that each operation completes fully before the next operation begins. Special…

Comment Plexicus détecte et corrige CWE-1265 ?

Le moteur SAST de Plexicus reconnaît la signature de flux de données de CWE-1265 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-1265 ?

MITRE publie la définition canonique à https://cwe.mitre.org/data/definitions/1265.html. Vous pouvez également consulter la documentation OWASP et NIST pour des conseils adjacents.

Faiblesses associées

Weaknesses related to CWE-1265

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CWE-662 Frère

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CWE-696 Frère

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CWE-705 Frère

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This vulnerability occurs when a program fails to return execution to the correct point in the code after finishing a specific operation…

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