CWE-374 Base Draft Medium likelihood

Passing Mutable Objects to an Untrusted Method

This vulnerability occurs when a function receives a direct reference to mutable data, such as an object or array, instead of a safe copy of that data.

Definition

What is CWE-374?

This vulnerability occurs when a function receives a direct reference to mutable data, such as an object or array, instead of a safe copy of that data.
When you pass a mutable object directly to a method—especially one from an external library or untrusted code—that method can alter or even delete the contents of your object. This breaks a fundamental assumption in your code: that the data you own remains under your control. The called function might change values, add unexpected elements, or clear the object entirely, leading to inconsistent states, crashes, or logic errors in your application. To prevent this, you should create and pass a defensive copy (a clone or deep copy) of the mutable data before sending it to any code you don't fully control. This ensures the original data remains intact and valid, regardless of what the external method does. Always treat mutable data passed across trust boundaries as potentially hostile and isolate it through copying.
Auswirkungen in der Praxis

Real-world CVEs caused by CWE-374

Bisher sind in MITREs Katalog keine öffentlichen CVE-Referenzen mit dieser CWE verknüpft.

Wie Angreifer es ausnutzen

Angreiferpfad Schritt für Schritt

  1. 1

    The following example demonstrates the weakness.

  2. 2

    In this example, bar and baz will be passed by reference to doOtherStuff() which may change them.

  3. 3

    In the following Java example, the BookStore class manages the sale of books in a bookstore, this class includes the member objects for the bookstore inventory and sales database manager classes. The BookStore class includes a method for updating the sales database and inventory when a book is sold. This method retrieves a Book object from the bookstore inventory object using the supplied ISBN number for the book class, then calls a method for the sales object to update the sales information and then calls a method for the inventory object to update inventory for the BookStore.

  4. 4

    However, in this example the Book object that is retrieved and passed to the method of the sales object could have its contents modified by the method. This could cause unexpected results when the book object is sent to the method for the inventory object to update the inventory.

  5. 5

    In the Java programming language arguments to methods are passed by value, however in the case of objects a reference to the object is passed by value to the method. When an object reference is passed as a method argument a copy of the object reference is made within the method and therefore both references point to the same object. This allows the contents of the object to be modified by the method that holds the copy of the object reference. [REF-374]

Verwundbares Codebeispiel

Vulnerable C

The following example demonstrates the weakness.

Verwundbar C 
private:
  	int foo;
  	complexType bar;
  	String baz;
  	otherClass externalClass;
  public:
  	void doStuff() {
  		externalClass.doOtherStuff(foo, bar, baz)
  	}
Sicheres Codebeispiel

Secure Java

To prevent the contents of the Book object from being modified, a copy of the Book object should be made before the method call to the sales object. In the following example a copy of the Book object is made using the clone() method and the copy of the Book object is passed to the method of the sales object. This will prevent any changes being made to the original Book object.

Sicher Java 
...
  public void updateSalesAndInventoryForBookSold(String bookISBN) {
```
// Get book object from inventory using ISBN* 
  		Book book = inventory.getBookWithISBN(bookISBN);
  		
  		 *// Create copy of book object to make sure contents are not changed* 
  		Book bookSold = (Book) book.clone();
  		
  		 *// update sales information for book sold* 
  		sales.updateSalesInformation(bookSold);
  		
  		 *// update inventory* 
  		inventory.updateInventory(book);}
  ...
What changed: the unsafe sink is replaced (or the input is validated/escaped) so the same payload no longer triggers the weakness.
Präventions-Checkliste

How to prevent CWE-374

  • Implementation Pass in data which should not be altered as constant or immutable.
  • Implementation Clone all mutable data before passing it into an external function . This is the preferred mitigation. This way, regardless of what changes are made to the data, a valid copy is retained for use by the class.
Erkennungssignale

How to detect CWE-374

SAST High

Führe statische Analyse (SAST) auf der Codebasis aus und suche im Datenfluss nach dem unsicheren Muster.

DAST Moderate

Führe dynamische Application-Security-Tests gegen den Live-Endpoint aus.

Runtime Moderate

Beobachte Runtime-Logs auf ungewöhnliche Exception-Traces, fehlerhafte Eingaben oder Versuche, Autorisierung zu umgehen.

Code review Moderate

Code Review: Markiere jeden neuen Code, der Eingaben von dieser Oberfläche ohne validierte Framework-Helper verarbeitet.

Plexicus Auto-Fix

Plexicus erkennt CWE-374 automatisch und öffnet in unter 60 Sekunden einen Fix-PR.

Codex Remedium scannt jeden Commit, identifiziert genau diese Schwachstelle und liefert einen reviewer-ready Pull Request mit dem Patch. Keine Tickets. Keine Hand-offs.

Demo anfordern Plexicus kostenlos testen
Häufig gestellte Fragen

Frequently asked questions

Was ist CWE-374?

This vulnerability occurs when a function receives a direct reference to mutable data, such as an object or array, instead of a safe copy of that data.

Wie gravierend ist CWE-374?

MITRE stuft die Exploit-Wahrscheinlichkeit als mittel ein — eine Ausnutzung ist realistisch, erfordert aber meist bestimmte Bedingungen.

Welche Sprachen oder Plattformen sind von CWE-374 betroffen?

MITRE lists the following affected platforms: C, C++, Java, C#.

Wie kann ich CWE-374 verhindern?

Pass in data which should not be altered as constant or immutable. Clone all mutable data before passing it into an external function . This is the preferred mitigation. This way, regardless of what changes are made to the data, a valid copy is retained for use by the class.

Wie erkennt und behebt Plexicus CWE-374?

Die SAST-Engine von Plexicus erkennt die Datenfluss-Signatur von CWE-374 bei jedem Commit. Bei einem Treffer öffnet unser Codex-Remedium-Agent einen Fix-PR mit korrigiertem Code, Tests und einer einzeiligen Zusammenfassung für den Reviewer.

Wo erfahre ich mehr über CWE-374?

MITRE veröffentlicht die kanonische Definition unter https://cwe.mitre.org/data/definitions/374.html. Für ergänzende Hinweise kannst du auch die OWASP- und NIST-Dokumentation heranziehen.

Verwandte Schwachstellen

Weaknesses related to CWE-374

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CWE-1189 Sibling

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CWE-1282 Sibling

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CWE-1327 Sibling

Binding to an Unrestricted IP Address

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CWE-1331 Sibling

Improper Isolation of Shared Resources in Network On Chip (NoC)

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CWE-134 Sibling

Use of Externally-Controlled Format String

This vulnerability occurs when a program uses a format string from an untrusted, external source (like user input, a network packet, or a…

CWE-200 Sibling

Exposure of Sensitive Information to an Unauthorized Actor

This weakness occurs when an application unintentionally reveals sensitive data to someone who shouldn't have access to it.

CWE-375 Sibling

Returning a Mutable Object to an Untrusted Caller

This vulnerability occurs when a method directly returns a reference to its internal mutable data, allowing untrusted calling code to…

CWE-377 Sibling

Insecure Temporary File

This vulnerability occurs when an application creates temporary files with insecure permissions or in predictable locations, allowing…

Ressourcen

Further reading

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