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Improper Restriction of Operations within the Bounds of a Memory Buffer

Stable Class
Structure: Simple
Description

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.

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.
Common Consequences 3
Scope: IntegrityConfidentialityAvailability

Impact: Execute Unauthorized Code or CommandsModify Memory

If the memory accessible by the attacker can be effectively controlled, it may be possible to execute arbitrary code, as with a standard buffer overflow. If the attacker can overwrite a pointer's worth of memory (usually 32 or 64 bits), they can alter the intended control flow by redirecting a function pointer to their own malicious code. Even when the attacker can only modify a single byte arbitrary code execution can be possible. Sometimes this is because the same problem can be exploited repeatedly to the same effect. Other times it is because the attacker can overwrite security-critical application-specific data -- such as a flag indicating whether the user is an administrator.

Scope: AvailabilityConfidentiality

Impact: Read MemoryDoS: Crash, Exit, or RestartDoS: Resource Consumption (CPU)DoS: Resource Consumption (Memory)

Out of bounds memory access will very likely result in the corruption of relevant memory, and perhaps instructions, possibly leading to a crash. Other attacks leading to lack of availability are possible, including putting the program into an infinite loop.

Scope: Confidentiality

Impact: Read Memory

In the case of an out-of-bounds read, the attacker may have access to sensitive information. If the sensitive information contains system details, such as the current buffer's position in memory, this knowledge can be used to craft further attacks, possibly with more severe consequences.
Detection Methods 9
Automated Static AnalysisHigh
This weakness can often be detected using automated static analysis tools. Many modern tools use data flow analysis or constraint-based techniques to minimize the number of false positives. Automated static analysis generally does not account for environmental considerations when reporting out-of-bounds memory operations. This can make it difficult for users to determine which warnings should be investigated first. For example, an analysis tool might report buffer overflows that originate from command line arguments in a program that is not expected to run with setuid or other special privileges.
Automated Dynamic Analysis
This weakness can be detected using dynamic tools and techniques that interact with the software using large test suites with many diverse inputs, such as fuzz testing (fuzzing), robustness testing, and fault injection. The software's operation may slow down, but it should not become unstable, crash, or generate incorrect results.
Automated Static Analysis - Binary or BytecodeSOAR Partial
According to SOAR [REF-1479], the following detection techniques may be useful: ``` Cost effective for partial coverage: ``` Binary / Bytecode Quality Analysis Bytecode Weakness Analysis - including disassembler + source code weakness analysis Binary Weakness Analysis - including disassembler + source code weakness analysis
Manual Static Analysis - Binary or BytecodeSOAR Partial
According to SOAR [REF-1479], the following detection techniques may be useful: ``` Cost effective for partial coverage: ``` Binary / Bytecode disassembler - then use manual analysis for vulnerabilities & anomalies
Dynamic Analysis with Automated Results InterpretationSOAR Partial
According to SOAR [REF-1479], the following detection techniques may be useful: ``` Cost effective for partial coverage: ``` Web Application Scanner Web Services Scanner Database Scanners
Dynamic Analysis with Manual Results InterpretationSOAR Partial
According to SOAR [REF-1479], the following detection techniques may be useful: ``` Cost effective for partial coverage: ``` Fuzz Tester Framework-based Fuzzer
Manual Static Analysis - Source CodeSOAR Partial
According to SOAR [REF-1479], the following detection techniques may be useful: ``` Cost effective for partial coverage: ``` Focused Manual Spotcheck - Focused manual analysis of source Manual Source Code Review (not inspections)
Automated Static Analysis - Source CodeHigh
According to SOAR [REF-1479], the following detection techniques may be useful: ``` Highly cost effective: ``` Source code Weakness Analyzer Context-configured Source Code Weakness Analyzer ``` Cost effective for partial coverage: ``` Source Code Quality Analyzer
Architecture or Design ReviewHigh
According to SOAR [REF-1479], the following detection techniques may be useful: ``` Highly cost effective: ``` Formal Methods / Correct-By-Construction ``` Cost effective for partial coverage: ``` Inspection (IEEE 1028 standard) (can apply to requirements, design, source code, etc.)
Potential Mitigations 7
Phase: Requirements

Strategy: Language Selection

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 a language's interface to native code may still be subject to overflows, even if the language itself is theoretically safe.
Phase: Architecture and Design

Strategy: Libraries or Frameworks

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.
Phase: OperationBuild and Compilation

Strategy: 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

Phase: 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 accessing the buffer in a loop and make sure there is no danger of writing past the allocated space. - If necessary, truncate all input strings to a reasonable length before passing them to the copy and concatenation functions.
Phase: OperationBuild and Compilation

Strategy: 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

Phase: Operation

Strategy: Environment Hardening

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 Execution Prevention) from D3FEND [REF-1336].

Effectiveness: Defense in Depth

Phase: Implementation
Replace unbounded copy functions with analogous functions that support length arguments, such as strcpy with strncpy. Create these if they are not available.

Effectiveness: Moderate
Demonstrative Examples 5

ID : DX-1

This example takes an IP address from a user, verifies that it is well formed and then looks up the hostname and copies it into a buffer.

Code Example:

Bad
C
c

/*routine that ensures user_supplied_addr is in the right format for conversion /

c
This function allocates a buffer of 64 bytes to store the hostname, however there is no guarantee that the hostname will not be larger than 64 bytes. If an attacker specifies an address which resolves to a very large hostname, then the function may overwrite sensitive data or even relinquish control flow to the attacker.
Note that this example also contains an unchecked return value (Unchecked Return Value) that can lead to a NULL pointer dereference (NULL Pointer Dereference).

ID : DX-19

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

Code Example:

Bad
C
c

/* encode to < / } else dst_buf[dst_index++] = user_supplied_string[i];} return dst_buf;}

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.

ID : DX-90

The following example asks a user for an offset into an array to select an item.

Code Example:

Bad
C
c
The programmer allows the user to specify which element in the list to select, however an attacker can provide an out-of-bounds offset, resulting in a buffer over-read (Buffer Over-read).

ID : DX-100

In the following code, the method retrieves a value from an array at a specific array index location that is given as an input parameter to the method

Code Example:

Bad
C
c

// check that the array index is less than the maximum*

c
c
However, this method only verifies that the given array index is less than the maximum length of the array but does not check for the minimum value (Numeric Range Comparison Without Minimum Check). This will allow a negative value to be accepted as the input array index, which will result in reading data before the beginning of the buffer (Buffer Under-read) and may allow access to sensitive memory. The input array index should be checked to verify that is within the maximum and minimum range required for the array (Improper Validation of Array Index). In this example the if statement should be modified to include a minimum range check, as shown below.

Code Example:

Good
C
c

// check that the array index is within the correct*

c
Windows provides the _mbs family of functions to perform various operations on multibyte strings. When these functions are passed a malformed multibyte string, such as a string containing a valid leading byte followed by a single null byte, they can read or write past the end of the string buffer causing a buffer overflow. The following functions all pose a risk of buffer overflow: _mbsinc _mbsdec _mbsncat _mbsncpy _mbsnextc _mbsnset _mbsrev _mbsset _mbsstr _mbstok _mbccpy _mbslen
Observed Examples 18
CVE-2021-22991Incorrect URI normalization in application traffic product leads to buffer overflow, as exploited in the wild per CISA KEV.
CVE-2020-29557Buffer overflow in Wi-Fi router web interface, as exploited in the wild per CISA KEV.
CVE-2009-2550Classic stack-based buffer overflow in media player using a long entry in a playlist
CVE-2009-2403Heap-based buffer overflow in media player using a long entry in a playlist
CVE-2009-0689large precision value in a format string triggers overflow
CVE-2009-0690negative offset value leads to out-of-bounds read
CVE-2009-1532malformed inputs cause accesses of uninitialized or previously-deleted objects, leading to memory corruption
CVE-2009-1528chain: lack of synchronization leads to memory corruption
CVE-2021-29529Chain: machine-learning product can have a heap-based buffer overflow (Heap-based Buffer Overflow) when some integer-oriented bounds are calculated by using ceiling() and floor() on floating point values (Insufficient Precision or Accuracy of a Real Number)
CVE-2009-0558attacker-controlled array index leads to code execution
CVE-2009-0269chain: -1 value from a function call was intended to indicate an error, but is used as an array index instead.
CVE-2009-0566chain: incorrect calculations lead to incorrect pointer dereference and memory corruption
CVE-2009-1350product accepts crafted messages that lead to a dereference of an arbitrary pointer
CVE-2009-0191chain: malformed input causes dereference of uninitialized memory
CVE-2008-4113OS kernel trusts userland-supplied length value, allowing reading of sensitive information
CVE-2005-1513Chain: integer overflow in securely-coded mail program leads to buffer overflow. In 2005, this was regarded as unrealistic to exploit, but in 2020, it was rediscovered to be easier to exploit due to evolutions of the technology.
CVE-2003-0542buffer overflow involving a regular expression with a large number of captures
CVE-2017-1000121chain: unchecked message size metadata allows integer overflow (Integer Overflow or Wraparound) leading to buffer overflow (Improper Restriction of Operations within the Bounds of a Memory Buffer).
References 18
Smashing The Stack For Fun And Profit
Aleph One
Phrack
08-11-1996
https://phrack.org/issues/49/14.html
ID: REF-1029
Writing Secure Code
Michael Howard and David LeBlanc
Microsoft Press
04-12-2002
https://www.microsoftpressstore.com/store/writing-secure-code-9780735617223
ID: REF-7
Using the Strsafe.h Functions
Microsoft
https://learn.microsoft.com/en-us/windows/win32/menurc/strsafe-ovw?redirectedfrom=MSDN(2023-04-07)
ID: REF-56
Safe C String Library v1.0.3
Matt Messier and John Viega
http://www.gnu-darwin.org/www001/ports-1.5a-CURRENT/devel/safestr/work/safestr-1.0.3/doc/safestr.html(2023-04-07)
ID: REF-57
Address Space Layout Randomization in Windows Vista
Michael Howard
https://learn.microsoft.com/en-us/archive/blogs/michael_howard/address-space-layout-randomization-in-windows-vista(2023-04-07)
ID: REF-58
Limiting buffer overflows with ExecShield
Arjan van de Ven
https://archive.is/saAFo(2023-04-07)
ID: REF-59
PaX
https://en.wikipedia.org/wiki/Executable_space_protection#PaX(2023-04-07)
ID: REF-60
Understanding DEP as a mitigation technology part 1
Microsoft
https://msrc.microsoft.com/blog/2009/06/understanding-dep-as-a-mitigation-technology-part-1/(2023-04-07)
ID: REF-61
The Art of Software Security Assessment
Mark Dowd, John McDonald, and Justin Schuh
Addison Wesley
2006
ID: REF-62
Position Independent Executables (PIE)
Grant Murphy
Red Hat
28-11-2012
https://www.redhat.com/en/blog/position-independent-executables-pie(2023-04-07)
ID: REF-64
Prelink and address space randomization
John Richard Moser
05-07-2006
https://lwn.net/Articles/190139/(2023-04-26)
ID: REF-1332
Jump Over ASLR: Attacking Branch Predictors to Bypass ASLR
Dmitry Evtyushkin, Dmitry Ponomarev, Nael Abu-Ghazaleh
2016
http://www.cs.ucr.edu/~nael/pubs/micro16.pdf(2023-04-26)
ID: REF-1333
Stack Frame Canary Validation (D3-SFCV)
D3FEND
2023
https://d3fend.mitre.org/technique/d3f:StackFrameCanaryValidation/(2023-04-26)
ID: REF-1334
Segment Address Offset Randomization (D3-SAOR)
D3FEND
2023
https://d3fend.mitre.org/technique/d3f:SegmentAddressOffsetRandomization/(2023-04-26)
ID: REF-1335
Process Segment Execution Prevention (D3-PSEP)
D3FEND
2023
https://d3fend.mitre.org/technique/d3f:ProcessSegmentExecutionPrevention/(2023-04-26)
ID: REF-1336
Bypassing Browser Memory Protections: Setting back browser security by 10 years
Alexander Sotirov and Mark Dowd
2008
https://www.blackhat.com/presentations/bh-usa-08/Sotirov_Dowd/bh08-sotirov-dowd.pdf(2023-04-26)
ID: REF-1337
Secure by Design Alert: Eliminating Buffer Overflow Vulnerabilities
Cybersecurity and Infrastructure Security Agency
12-02-2025
https://www.cisa.gov/resources-tools/resources/secure-design-alert-eliminating-buffer-overflow-vulnerabilities(2025-07-18)
ID: REF-1477
State-of-the-Art Resources (SOAR) for Software Vulnerability Detection, Test, and Evaluation
Gregory Larsen, E. Kenneth Hong Fong, David A. Wheeler, and Rama S. Moorthy
07-2014
https://www.ida.org/-/media/feature/publications/s/st/stateoftheart-resources-soar-for-software-vulnerability-detection-test-and-evaluation/p-5061.ashx(2025-09-05)
ID: REF-1479
Likelihood of Exploit

High

Applicable Platforms
Languages:
C : OftenC++ : OftenAssembly : Undetermined
Modes of Introduction
Implementation
Related Attack Patterns
Alternate Terms

Buffer Overflow

This term has many different meanings to different audiences. From a CWE mapping perspective, this term should be avoided where possible. Some researchers, developers, and tools intend for it to mean "write past the end of a buffer," whereas others use the same term to mean "any read or write outside the boundaries of a buffer, whether before the beginning of the buffer or after the end of the buffer." Others could mean "any action after the end of a buffer, whether it is a read or write." Since the term is commonly used for exploitation and for vulnerabilities, it further confuses things.

buffer overrun

Some prominent vendors and researchers use the term "buffer overrun," but most people use "buffer overflow." See the alternate term for "buffer overflow" for context.

memory safety

Generally used for techniques that avoid weaknesses related to memory access, such as those identified by Improper Restriction of Operations within the Bounds of a Memory Buffer and its descendants. However, the term is not formal, and there is likely disagreement between practitioners as to which weaknesses are implicitly covered by the "memory safety" term.
Functional Areas
  1. Memory Management
Affected Resources
  1. Memory
Related Weaknesses
ChildOf: Incorrect Access of Indexable Resource ('Range Error') (CWE-118)
ChildOf: Improper Input Validation (CWE-20)
Taxonomy Mapping
  • OWASP Top Ten 2004
  • CERT C Secure Coding
  • CERT C Secure Coding
  • CERT C Secure Coding
  • CERT C Secure Coding
  • CERT C Secure Coding
  • CERT C Secure Coding
  • CERT C Secure Coding
  • CERT C Secure Coding
  • WASC
  • Software Fault Patterns
Notes
Applicable Platform It is possible in any programming languages without memory management support to attempt an operation outside of the bounds of a memory buffer, but the consequences will vary widely depending on the language, platform, and chip architecture.