Run static analysis (SAST) on the codebase looking for the unsafe pattern in the data flow.
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.
Real-world impact
Real-world CVEs caused by CWE-762
No public CVE references are linked to this CWE in MITRE's catalog yet.
How attackers exploit it
Step-by-step attacker path
- 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.
Vulnerable code example
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);} Secure code example
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.
Prevention checklist
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.
Detection signals
How to detect CWE-762
Run dynamic application security testing against the live endpoint.
Watch runtime logs for unusual exception traces, malformed input, or authorization bypass attempts.
Code review: flag any new code that handles input from this surface without using the validated framework helpers.
Plexicus auto-detects CWE-762 and opens a fix PR in under 60 seconds.
Codex Remedium scans every commit, identifies this exact weakness, and ships a reviewer-ready pull request with the patch. No tickets. No hand-offs.
Frequently asked questions What is CWE-762?
How serious is CWE-762?
What languages or platforms are affected by CWE-762?
How can I prevent CWE-762?
How does Plexicus detect and fix CWE-762?
Where can I learn more about CWE-762?
Frequently asked questions
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.
How serious is CWE-762?
MITRE rates the likelihood of exploit as Low — exploitation is uncommon, but the weakness should still be fixed when discovered.
What languages or platforms are affected by CWE-762?
MITRE lists the following affected platforms: C, C++.
How can I prevent CWE-762?
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…
How does Plexicus detect and fix CWE-762?
Plexicus's SAST engine matches the data-flow signature for CWE-762 on every commit. When a match is found, our Codex Remedium agent opens a fix PR with the corrected code, tests, and a one-line summary for the reviewer.
Where can I learn more about CWE-762?
MITRE publishes the canonical definition at https://cwe.mitre.org/data/definitions/762.html. You can also reference OWASP and NIST documentation for adjacent guidance.
Related weaknesses
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…
Resources
Further reading
- MITRE — official 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
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