CWE-416βUse After Free
PUBLISHEDweakness recordHigh
released 2006-07-19 Β· last modified 2026-04-30
Metadata
- CWE ID:
- CWE-416
- Abstraction:
- Variant
- Structure:
- Simple
- Status:
- Stable
- Release Date:
- 2006-07-19
- Latest Modification Date:
- 2026-04-30
Weakness Name
Use After Free
Description
The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory "belongs" to the code that operates on the new pointer.
Common Consequences
- Scope:
- Integrity
- Impact:
- Modify Memory
- Notes:
- The use of previously freed memory may corrupt valid data, if the memory area in question has been allocated and used properly elsewhere.
- Scope:
- Availability
- Impact:
- DoS: Crash, Exit, or Restart
- Notes:
- If chunk consolidation occurs after the use of previously freed data, the process may crash when invalid data is used as chunk information.
- Scope:
- Confidentiality
- Impact:
- Read Memory
- Notes:
- Read operations on freed memory can sometimes leak sensitive information instead of causing a crash
- Scope:
- Integrity, Confidentiality, Availability
- Impact:
- Execute Unauthorized Code or Commands
- Notes:
- If malicious data is entered before chunk consolidation can take place, it may be possible to take advantage of a write-what-where primitive to execute arbitrary code. If the newly allocated data happens to hold a class, in C++ for example, various function pointers may be scattered within the heap data. If one of these function pointers is overwritten with an address to valid shellcode, execution of arbitrary code can be achieved.
