CWE-374: Passing Mutable Objects to an Untrusted Method

Extended Description

The function or method that has been called can alter or delete the mutable data. This could violate assumptions that the calling function has made about its state. In situations where unknown code is called with references to mutable data, this external code could make changes to the data sent. If this data was not previously cloned, the modified data might not be valid in the context of execution.

Code Examples & CVEs

Demonstrative Examples

The following example demonstrates the weakness.

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

BadC

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

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.

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.

BadJava

public class BookStore {                         private BookStoreInventory inventory;private SalesDBManager sales;...                            // constructor for BookStore                            public BookStore() {this.inventory = new BookStoreInventory();this.sales = new SalesDBManager();...}public void updateSalesAndInventoryForBookSold(String bookISBN) {                                                                                                   // Get book object from inventory using ISBN                                  Book book = inventory.getBookWithISBN(bookISBN);                                  // update sales information for book sold                                  sales.updateSalesInformation(book);                                  // update inventory                                  inventory.updateInventory(book);                            }                            // other BookStore methods                            ...                      }public class Book {private String title;private String author;private String isbn;                         // Book object constructors and get/set methods                         ...}

GoodJava

...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);                      }...

Source-backed guidance

Additional facts reviewed against primary or authoritative security sources.

Verify controls for CWE-374 with SSDF evidence

Use NIST SSDF verification and vulnerability-response practices to detect CWE-374, Passing Mutable Objects to an Untrusted Method, throughout the product lifecycle. Derive review questions, static or dynamic checks, and negative tests from the CWE's causal behavior; define the components and lifecycle stages each check covers; and retain findings with enough evidence to distinguish the root cause from symptoms and impacts. Track escapes and false negatives, then improve the verification plan after every confirmed occurrence.

NIST SP 800-218 Secure Software Development Framework — National Institute of Standards and Technology

Address Passing Mutable Objects to an Untrusted Method during Implementation

MITRE associates mitigation with Implementation; recorded impacts include Modify Memory; related weaknesses include CWE-668. Use these source-defined anchors to turn CWE-374 into implementation, review, and verification checks for the affected component.

CWE-374: Passing Mutable Objects to an Untrusted Method — MITRE CWE

Triage CWE-374 against known exploitation evidence

Use CISA's Known Exploited Vulnerabilities catalog to test whether a vulnerability mapped to CWE-374, Passing Mutable Objects to an Untrusted Method, has evidence of exploitation in the wild. Confirm the CVE-to-CWE root-cause mapping independently before attaching the example, then capture the affected product, required action, and remediation deadline. A missing KEV match is not evidence that the weakness is unexploited, and a KEV entry must not be generalized to every occurrence of this CWE.

Known Exploited Vulnerabilities Catalog — Cybersecurity and Infrastructure Security Agency

Apply precise root-cause mapping to CWE-374

Apply MITRE's full root-cause mapping guidance when using CWE-374, Passing Mutable Objects to an Untrusted Method. Separate weakness language from attacker prerequisites and technical impact, check the entry's abstraction and vulnerability-mapping notes, and prefer the most specific Base or Variant supported by the evidence. Record the rejected alternatives and require an independent review before the mapping is used for remediation trends or program metrics.

CVE to CWE Root Cause Mapping Guidance — MITRE CWE

Validate CWE-374 with root-cause mapping checks

Apply MITRE's root-cause mapping quick tips to CWE-374, Passing Mutable Objects to an Untrusted Method. Confirm the finding describes the causal weakness rather than an impact or attack pattern, compare the abstraction and mapping notes with plausible alternatives, and have a second reviewer challenge the selection. Preserve the evidence and reasoning so recurring defects can be measured against one consistent identifier.

CVE to CWE Root Cause Mapping Quick Tips — MITRE CWE

Frequently Asked Questions

What is CWE-374: Passing Mutable Objects to an Untrusted Method?+

CWE-374: Passing Mutable Objects to an Untrusted Method is a Common Weakness Enumeration (CWE) entry maintained by MITRE. The product sends non-cloned mutable data as an argument to a method or function. The function or method that has been called can alter or delete the mutable data. This could violate assumptions that the calling function has made about its state. In situations where unknown code is called with references to mutable data, this external code could make changes to the data sent. If this data was not previously cloned, the modified data might not be valid in the context of execution.

What are the security consequences of Passing Mutable Objects to an Untrusted Method?+

If exploited, CWE-374 (Passing Mutable Objects to an Untrusted Method) it can compromise Integrity, leading to outcomes such as Modify Memory.

How do you prevent or mitigate Passing Mutable Objects to an Untrusted Method?+

Recommended mitigations for CWE-374 include: 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.

Which programming languages are affected by Passing Mutable Objects to an Untrusted Method?+

CWE-374 commonly affects C, C++, Java, C# and Object-Oriented. Note that weaknesses are often language-agnostic patterns, so secure coding practices apply broadly.

What is the difference between a CWE and a CVE?+

A CWE (Common Weakness Enumeration) like CWE-374 describes a category of software weakness — the underlying flaw type. A CVE (Common Vulnerabilities and Exposures) identifies a specific, real-world vulnerability in a particular product. In short, a CWE is the kind of mistake, and a CVE is an instance of that mistake being found in software.

CWE-374: Passing Mutable Objects to an Untrusted Method

Extended Description

Technical Details

Applicable To

Security Consequences

Scope

Impact

Mitigation Strategies

Phase

Description