CWE WEAKNESSES / CWE-119
CWE-119
Improper Restriction of Operations within the Bounds of a Memory Buffer
Class EXPLOIT LIKELIHOOD: HIGH
What it is
The product performs operations on a memory buffer, but it reads from or writes to a memory location outside the buffer's intended boundary. This may result in read or write operations on unexpected memory locations that could be linked to other variables, data structures, or internal program data.
Impact
| Integrity, Confidentiality, Availability | Execute Unauthorized Code or Commands, Modify Memory |
| Availability, Confidentiality | Read Memory, DoS: Crash, Exit, or Restart, DoS: Resource Consumption (CPU), DoS: Resource Consumption (Memory) |
| Confidentiality | Read Memory |
Mitigations
- [Requirements]Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.For example, many languages that perform their own memory management, such as Java and Perl, are not subject to buffer overflows. Other languages, such as Ada and C#, typically provide overflow protection, but the protection can be disabled by the programmer.Be wary that
- [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.Examples include the Safe C String Library (SafeStr) by Messier and Viega [REF-57], and the Strsafe.h library from Microsoft [REF-56]. These libraries provide safer versions of overflow-prone string-handling functions.
- [Operation, Build and Compilation]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] dis
- [Implementation]Consider adhering to the following rules when allocating and managing an application's memory:- Double check that the buffer is as large as specified.- When using functions that accept a number of bytes to copy, such as strncpy(), be aware that if the destination buffer size is equal to the source buffer size, it may not NULL-terminate the string.- Check buffer boundaries if accessi
- [Operation, Build and Compilation]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]. Im
- [Operation]Use a CPU and operating system that offers Data Execution Protection (using hardware NX or XD bits) or the equivalent techniques that simulate this feature in software, such as PaX [REF-60] [REF-61]. These techniques ensure that any instruction executed is exclusively at a memory address that is part of the code segment.For more information on these techniques see D3-PSEP (Process Segment
- [Implementation] Replace unbounded copy functions with analogous functions that support length arguments, such as strcpy with strncpy. Create these if they are not available.
Real-world CVE examples
- CVE-2021-22991 — Incorrect URI normalization in application traffic product leads to buffer overflow, as exploited in the wild per CISA KEV.
- CVE-2025-47153 — Chain: build process for JavaScript runtime environment can have inconsistent sizes for off_t (CWE-1102), allowing out-of-bounds access / segmentation fault (CW
- CVE-2020-29557 — Buffer overflow in Wi-Fi router web interface, as exploited in the wild per CISA KEV.
- CVE-2009-2550 — Classic stack-based buffer overflow in media player using a long entry in a playlist
- CVE-2009-2403 — Heap-based buffer overflow in media player using a long entry in a playlist
- CVE-2009-0689 — large precision value in a format string triggers overflow
- CVE-2009-0690 — negative offset value leads to out-of-bounds read
- CVE-2009-1532 — malformed inputs cause accesses of uninitialized or previously-deleted objects, leading to memory corruption
- CVE-2009-1528 — chain: lack of synchronization leads to memory corruption
- 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()
- CVE-2009-0558 — attacker-controlled array index leads to code execution
- CVE-2009-0269 — chain: -1 value from a function call was intended to indicate an error, but is used as an array index instead.
Related weaknesses
Test & detect
Browse all common weaknesses, check related exploited CVEs, or map to ATT&CK techniques.
Source: MITRE CWE. View on cwe.mitre.org →