What CVEs are caused by CWE-122?

2,270 recorded CVEs are attributed to CWE-122, including CVE-2024-38812, CVE-2025-21333, CVE-2023-27997. 17 are listed in CISA's Known Exploited Vulnerabilities (KEV) catalog.

What are the consequences of CWE-122?

Exploiting CWE-122 can lead to: DoS: Crash, Exit, or Restart, DoS: Resource Consumption (CPU), DoS: Resource Consumption (Memory), Execute Unauthorized Code or Commands, Bypass Protection Mechanism, Modify Memory.

Is CWE-122 actively exploited?

Yes. 17 CWE-122 vulnerabilities are in CISA's KEV catalog of actively exploited flaws, out of 2,270 recorded CVEs.

Variant weakness

Draft

CWE-122: Heap-based Buffer Overflow

Also known as: Heap Overflow, Heap Buffer Overflow

A heap overflow condition is a buffer overflow, where the buffer that can be overwritten is allocated in the heap portion of memory, generally meaning that the buffer was allocated using a routine such as malloc().

Last updated May 1, 2026

2,270

Recorded CVEs

With this primary weakness

KEVs

In the CISA KEV catalog

High

Likelihood of exploit

Per MITRE

Variant

Abstraction

MITRE classification

Overview

CWE-122 (Heap-based Buffer Overflow) is a variant-level software weakness catalogued by MITRE in the Common Weakness Enumeration (CWE). It describes a recurring type of mistake that can lead to exploitable security vulnerabilities.

Real-world CVEs

2,270 recorded CVEs are caused by CWE-122 (Heap-based Buffer Overflow), including 17 in CISA's KEV (Known Exploited Vulnerabilities) catalog. KEVs are shown first. 537 new CWE-122 CVEs have been recorded so far in 2026 (502 in 2025).

Showing 12 of 2,270 recorded CWE-122 CVEs. Track new ones as they are published and get AI-written analysis and fixes.

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Common consequences

What can happen when CWE-122 is exploited.

DoS: Crash, Exit, or Restart, DoS: Resource Consumption (CPU), DoS: Resource Consumption (Memory)

Affects: Availability

Buffer overflows generally lead to crashes. Other attacks leading to lack of availability are possible, including putting the program into an infinite loop.

Execute Unauthorized Code or Commands, Bypass Protection Mechanism, Modify Memory

Affects: Integrity, Confidentiality, Availability, Access Control

Buffer overflows often can be used to execute arbitrary code, which is usually outside the scope of a program's implicit security policy. Besides important user data, heap-based overflows can be used to overwrite function pointers that may be living in memory, pointing it to the attacker's code. Even in applications that do not explicitly use function pointers, the run-time will usually leave many in memory. For example, object methods in C++ are generally implemented using function pointers. Even in C programs, there is often a global offset table used by the underlying runtime.

Execute Unauthorized Code or Commands, Bypass Protection Mechanism, Other

Affects: Integrity, Confidentiality, Availability, Access Control, Other

When the consequence is arbitrary code execution, this can often be used to subvert any other security service.

How it happens

When it is introduced

Typically introduced during these phases of the software lifecycle.

Implementation

Applies to

Languages

Memory-Unsafe (Often)

C (Often)

C++ (Often)

How to prevent it

Practical mitigations for CWE-122, grouped by where in the lifecycle they apply.

Pre-design: Use a language or compiler that performs automatic bounds checking.

Architecture and Design

Use an abstraction library to abstract away risky APIs. Not a complete solution.

Operation

Build and Compilation

Environment Hardening

Use automatic buffer overflow detection mechanisms that are offered by certain compilers or compiler extensions. Examples include: the Microsoft Visual Studio /GS flag, Fedora/Red Hat FORTIFY_SOURCE GCC flag, StackGuard, and ProPolice, which provide various mechanisms including canary-based detection and range/index checking.

D3-SFCV (Stack Frame Canary Validation) from D3FEND [REF-1334] discusses canary-based detection in detail.

Effectiveness: Defense in Depth

Operation

Build and Compilation

Environment Hardening

Run or compile the software using features or extensions that randomly arrange the positions of a program's executable and libraries in memory. Because this makes the addresses unpredictable, it can prevent an attacker from reliably jumping to exploitable code.

Examples include Address Space Layout Randomization (ASLR) [REF-58] [REF-60] and Position-Independent Executables (PIE) [REF-64]. Imported modules may be similarly realigned if their default memory addresses conflict with other modules, in a process known as "rebasing" (for Windows) and "prelinking" (for Linux) [REF-1332] using randomly generated addresses. ASLR for libraries cannot be used in conjunction with prelink since it would require relocating the libraries at run-time, defeating the whole purpose of prelinking.

For more information on these techniques see D3-SAOR (Segment Address Offset Randomization) from D3FEND [REF-1335].

Effectiveness: Defense in Depth — These techniques do not provide a complete solution. For instance, exploits frequently use a bug that discloses memory addresses in order to maximize reliability of code execution [REF-1337]. It has also been shown that a side-channel attack can bypass ASLR [REF-1333].

Implementation

Implement and perform bounds checking on input.

Implementation

Libraries or Frameworks

Do not use dangerous functions such as gets. Look for their safe equivalent, which checks for the boundary.

Operation

Use OS-level preventative functionality. This is not a complete solution, but it provides some defense in depth.

How to detect it

Fuzzing

Fuzz testing (fuzzing) is a powerful technique for generating large numbers of diverse inputs - either randomly or algorithmically - and dynamically invoking the code with those inputs. Even with random inputs, it is often capable of generating unexpected results such as crashes, memory corruption, or resource consumption. Fuzzing effectively produces repeatable test cases that clearly indicate bugs, which helps developers to diagnose the issues.

Effectiveness: High

Automated Dynamic Analysis

Use tools that are integrated during compilation to insert runtime error-checking mechanisms related to memory safety errors, such as AddressSanitizer (ASan) for C/C++ [REF-1518].

Effectiveness: Moderate

Code examples

Illustrative examples from MITRE showing how the weakness appears in code.

While buffer overflow examples can be rather complex, it is possible to have very simple, yet still exploitable, heap-based buffer overflows:

Vulnerable example

#define BUFSIZE 256

The buffer is allocated heap memory with a fixed size, but there is no guarantee the string in argv[1] will not exceed this size and cause an overflow.

This example applies an encoding procedure to an input string and stores it into a buffer.

Vulnerable example

char * copy_input(char *user_supplied_string){

The programmer attempts to encode the ampersand character in the user-controlled string, however the length of the string is validated before the encoding procedure is applied. Furthermore, the programmer assumes encoding expansion will only expand a given character by a factor of 4, while the encoding of the ampersand expands by 5. As a result, when the encoding procedure expands the string it is possible to overflow the destination buffer if the attacker provides a string of many ampersands.

Illustrative examples

Real CVEs that MITRE cites as examples of this weakness.

CVE-2025-46687 — Chain: Javascript engine code does not perform a length check (CWE-1284) leading to integer overflow (CWE-190) causing allocation of smaller buffer than expected (CWE-131) resulting in a heap-based buffer overflow (CWE-122)
CVE-2021-43537 — Chain: in a web browser, an unsigned 64-bit integer is forcibly cast to a 32-bit integer (CWE-681) and potentially leading to an integer overflow (CWE-190). If an integer overflow occurs, this can cause heap memory corruption (CWE-122)
CVE-2007-4268 — Chain: integer signedness error (CWE-195) passes signed comparison, leading to heap overflow (CWE-122)
CVE-2009-2523 — Chain: product does not handle when an input string is not NULL terminated (CWE-170), leading to buffer over-read (CWE-125) or heap-based buffer overflow (CWE-122).
CVE-2021-29529 — Chain: machine-learning product can have a heap-based buffer overflow (CWE-122) when some integer-oriented bounds are calculated by using ceiling() and floor() on floating point values (CWE-1339)
CVE-2010-1866 — Chain: integer overflow (CWE-190) causes a negative signed value, which later bypasses a maximum-only check (CWE-839), leading to heap-based buffer overflow (CWE-122).

Terminology & mappings

Alternate terms

Heap Overflow
Heap Buffer Overflow

Mapped taxonomies

CLASP: Heap overflow
Software Fault Patterns: Faulty Buffer Access (SFP8)
CERT C Secure Coding: Guarantee that storage for strings has sufficient space for character data and the null terminator (STR31-C) — CWE More Specific fit
ISA/IEC 62443: Req CR 3.5 (Part 4-2)
ISA/IEC 62443: Req SR 3.5 (Part 3-3)
ISA/IEC 62443: Req SI-1 (Part 4-1)
ISA/IEC 62443: Req SI-2 (Part 4-1)
ISA/IEC 62443: Req SVV-1 (Part 4-1)
ISA/IEC 62443: Req SVV-3 (Part 4-1)

Attack patterns

CAPEC attack patterns that exploit this weakness.

CAPEC-92: Forced Integer Overflow

Frequently asked questions

Common questions about CWE-122.

What is CWE-122?: A heap overflow condition is a buffer overflow, where the buffer that can be overwritten is allocated in the heap portion of memory, generally meaning that the buffer was allocated using a routine such as malloc().
What CVEs are caused by CWE-122?: 2,270 recorded CVEs are attributed to CWE-122, including CVE-2024-38812, CVE-2025-21333, CVE-2023-27997. 17 are listed in CISA's Known Exploited Vulnerabilities (KEV) catalog.
How do you prevent CWE-122?: Pre-design: Use a language or compiler that performs automatic bounds checking.
How is CWE-122 detected?: Fuzzing: Fuzz testing (fuzzing) is a powerful technique for generating large numbers of diverse inputs - either randomly or algorithmically - and dynamically invoking the code with those inputs. Even with random inputs, it is often capable of generating unexpected results such as crashes, memory corruption, or resource consumption. Fuzzing effectively produces repeatable test cases that clearly indicate bugs, which helps developers to diagnose the issues.
What are the consequences of CWE-122?: Exploiting CWE-122 can lead to: DoS: Crash, Exit, or Restart, DoS: Resource Consumption (CPU), DoS: Resource Consumption (Memory), Execute Unauthorized Code or Commands, Bypass Protection Mechanism, Modify Memory.
Is CWE-122 actively exploited?: Yes. 17 CWE-122 vulnerabilities are in CISA's KEV catalog of actively exploited flaws, out of 2,270 recorded CVEs.

References

Weakness data is sourced from the MITRE CWE catalog (v4.20). CVE associations are aggregated and kept current by RadicalNotion.AI.

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Overview

Real-world CVEs

Common consequences

How it happens

When it is introduced

Applies to

How to prevent it

How to detect it

Fuzzing

Automated Dynamic Analysis

Code examples

Illustrative examples

Related weaknesses

Parent

Terminology & mappings

Alternate terms

Mapped taxonomies

Attack patterns

Frequently asked questions

References

Stay ahead of CWE-122