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CWE-762 Variant Incomplete
Mismatched Memory Management Routines
This vulnerability occurs when a program uses incompatible functions to allocate and free memory. For example, freeing memory with a function that doesn't match the one used to create it, like…
Definition
What is CWE-762?
This vulnerability occurs when a program uses incompatible functions to allocate and free memory. For example, freeing memory with a function that doesn't match the one used to create it, like mixing different memory management systems.
Mismatched memory management happens when allocation and deallocation routines come from incompatible sources. Common examples include trying to free stack-allocated memory with `free()` (which only works for heap memory), or allocating with C's `malloc()` but deallocating with C++'s `delete` operator. These functions manage memory in fundamentally different ways, and swapping them breaks the underlying memory manager's expectations.
The consequences range from immediate crashes and data corruption to more severe security issues like memory corruption exploits that could lead to arbitrary code execution. The severity depends on the specific routines involved, the program's memory layout, and whether an attacker can control or influence the mismatched operation.
Auswirkungen in der Praxis
Real-world CVEs caused by CWE-762
Bisher sind in MITREs Katalog keine öffentlichen CVE-Referenzen mit dieser CWE verknüpft.
Wie Angreifer es ausnutzen
Angreiferpfad Schritt für Schritt
- 1
This example allocates a BarObj object using the new operator in C++, however, the programmer then deallocates the object using free(), which may lead to unexpected behavior.
- 2
Instead, the programmer should have either created the object with one of the malloc family functions, or else deleted the object with the delete operator.
- 3
In this example, the program does not use matching functions such as malloc/free, new/delete, and new[]/delete[] to allocate/deallocate the resource.
- 4
In this example, the program calls the delete[] function on non-heap memory.
Verwundbares Codebeispiel
Vulnerable C++
This example allocates a BarObj object using the new operator in C++, however, the programmer then deallocates the object using free(), which may lead to unexpected behavior.
void foo(){
BarObj *ptr = new BarObj()
```
/* do some work with ptr here */*
...
free(ptr);} Sicheres Codebeispiel
Secure C++
Instead, the programmer should have either created the object with one of the malloc family functions, or else deleted the object with the delete operator.
void foo(){
BarObj *ptr = new BarObj()
```
/* do some work with ptr here */*
...
delete ptr;} 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-762
- Implementation Only call matching memory management functions. Do not mix and match routines. For example, when you allocate a buffer with malloc(), dispose of the original pointer with free().
- Implementation Choose a language or tool that provides automatic memory management, or makes manual memory management less error-prone. For example, glibc in Linux provides protection against free of invalid pointers. When using Xcode to target OS X or iOS, enable automatic reference counting (ARC) [REF-391]. To help correctly and consistently manage memory when programming in C++, consider using a smart pointer class such as std::auto_ptr (defined by ISO/IEC ISO/IEC 14882:2003), std::shared_ptr and std::unique_ptr (specified by an upcoming revision of the C++ standard, informally referred to as C++ 1x), or equivalent solutions such as Boost.
- Architecture and Design Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. For example, glibc in Linux provides protection against free of invalid pointers.
- Architecture and Design Use a language that provides abstractions for memory allocation and deallocation.
- Testing Use a tool that dynamically detects memory management problems, such as valgrind.
Erkennungssignale
How to detect CWE-762
Führe dynamische Application-Security-Tests gegen den Live-Endpoint aus.
Beobachte Runtime-Logs auf ungewöhnliche Exception-Traces, fehlerhafte Eingaben oder Versuche, Autorisierung zu umgehen.
Code Review: Markiere jeden neuen Code, der Eingaben von dieser Oberfläche ohne validierte Framework-Helper verarbeitet.
CWE-762
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.
Häufig gestellte Fragen Was ist CWE-762?
Wie gravierend ist CWE-762?
Welche Sprachen oder Plattformen sind von CWE-762 betroffen?
Wie kann ich CWE-762 verhindern?
Wie erkennt und behebt Plexicus CWE-762?
Wo erfahre ich mehr über CWE-762?
Frequently asked questions
Was ist CWE-762?
This vulnerability occurs when a program uses incompatible functions to allocate and free memory. For example, freeing memory with a function that doesn't match the one used to create it, like mixing different memory management systems.
Wie gravierend ist CWE-762?
MITRE stuft die Exploit-Wahrscheinlichkeit als niedrig ein — eine Ausnutzung ist selten, die Schwachstelle sollte aber dennoch behoben werden, sobald sie entdeckt wird.
Welche Sprachen oder Plattformen sind von CWE-762 betroffen?
MITRE lists the following affected platforms: C, C++.
Wie kann ich CWE-762 verhindern?
Only call matching memory management functions. Do not mix and match routines. For example, when you allocate a buffer with malloc(), dispose of the original pointer with free(). Choose a language or tool that provides automatic memory management, or makes manual memory management less error-prone. For example, glibc in Linux provides protection against free of invalid pointers. When using Xcode to target OS X or iOS, enable automatic reference counting (ARC) [REF-391]. To help correctly and…
Wie erkennt und behebt Plexicus CWE-762?
Die SAST-Engine von Plexicus erkennt die Datenfluss-Signatur von CWE-762 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-762?
MITRE veröffentlicht die kanonische Definition unter https://cwe.mitre.org/data/definitions/762.html. Für ergänzende Hinweise kannst du auch die OWASP- und NIST-Dokumentation heranziehen.
Verwandte Schwachstellen
Weaknesses related to CWE-762
CWE-763 Parent
Release of Invalid Pointer or Reference
This vulnerability occurs when a program tries to free a memory resource back to the system but uses an incorrect deallocation method or…
CWE-761 Sibling
Free of Pointer not at Start of Buffer
This vulnerability occurs when a program incorrectly frees a memory pointer that no longer points to the beginning of the allocated heap…
CWE-590 Child
Free of Memory not on the Heap
This vulnerability occurs when a program calls free() on a memory pointer that wasn't originally allocated using standard heap functions…
Ressourcen
Further reading
- MITRE — offizielle CWE-762 https://cwe.mitre.org/data/definitions/762.html
- boost C++ Library Smart Pointers https://www.boost.org/doc/libs/1_38_0/libs/smart_ptr/smart_ptr.htm
- Valgrind https://valgrind.org/
- Transitioning to ARC Release Notes https://developer.apple.com/library/archive/releasenotes/ObjectiveC/RN-TransitioningToARC/Introduction/Introduction.html
Bereit, das Wesentliche zu validieren?
Bereit zu validieren, was zählt.
Plexicus ist Proof-Driven AppSec: validierte Funde, kontextuelles Verständnis und geprüfte Remediation — in Evidenz verankert, mit Ihnen gescoped.