CWE - CWE-188: Reliance on Data/Memory Layout (4.18)

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CWE Glossary Definition

CWE-188: Reliance on Data/Memory Layout

Weakness ID: 188

Vulnerability Mapping: ALLOWED This CWE ID may be used to map to real-world vulnerabilities
Abstraction: Base Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.

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Description

The product makes invalid assumptions about how protocol data or memory is organized at a lower level, resulting in unintended program behavior.

Extended Description

When changing platforms or protocol versions, in-memory organization of data may change in unintended ways. For example, some architectures may place local variables A and B right next to each other with A on top; some may place them next to each other with B on top; and others may add some padding to each. The padding size may vary to ensure that each variable is aligned to a proper word size.

In protocol implementations, it is common to calculate an offset relative to another field to pick out a specific piece of data. Exceptional conditions, often involving new protocol versions, may add corner cases that change the data layout in an unusual way. The result can be that an implementation accesses an unintended field in the packet, treating data of one type as data of another type.

Common Consequences

Section HelpThis table specifies different individual consequences associated with the weakness. The Scope identifies the application security area that is violated, while the Impact describes the negative technical impact that arises if an adversary succeeds in exploiting this weakness. The Likelihood provides information about how likely the specific consequence is expected to be seen relative to the other consequences in the list. For example, there may be high likelihood that a weakness will be exploited to achieve a certain impact, but a low likelihood that it will be exploited to achieve a different impact.

Impact	Details
Modify Memory; Read Memory	Scope: Integrity, Confidentiality Can result in unintended modifications or exposure of sensitive memory.

Potential Mitigations

Phase(s)	Mitigation
Implementation; Architecture and Design	In flat address space situations, never allow computing memory addresses as offsets from another memory address.
Architecture and Design	Fully specify protocol layout unambiguously, providing a structured grammar (e.g., a compilable yacc grammar).
Testing	Testing: Test that the implementation properly handles each case in the protocol grammar.

Relationships

Section Help This table shows the weaknesses and high level categories that are related to this weakness. These relationships are defined as ChildOf, ParentOf, MemberOf and give insight to similar items that may exist at higher and lower levels of abstraction. In addition, relationships such as PeerOf and CanAlsoBe are defined to show similar weaknesses that the user may want to explore.

Relevant to the view "Research Concepts" (View-1000)

Nature	Type	ID	Name
ChildOf	Pillar Pillar - a weakness that is the most abstract type of weakness and represents a theme for all class/base/variant weaknesses related to it. A Pillar is different from a Category as a Pillar is still technically a type of weakness that describes a mistake, while a Category represents a common characteristic used to group related things.	435	Improper Interaction Between Multiple Correctly-Behaving Entities
ChildOf	Base Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.	1105	Insufficient Encapsulation of Machine-Dependent Functionality
ParentOf	Variant Variant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.	198	Use of Incorrect Byte Ordering

Modes Of Introduction

Section HelpThe different Modes of Introduction provide information about how and when this weakness may be introduced. The Phase identifies a point in the life cycle at which introduction may occur, while the Note provides a typical scenario related to introduction during the given phase.

Phase	Note
Implementation

Applicable Platforms

Section HelpThis listing shows possible areas for which the given weakness could appear. These may be for specific named Languages, Operating Systems, Architectures, Paradigms, Technologies, or a class of such platforms. The platform is listed along with how frequently the given weakness appears for that instance.

Languages

C (Undetermined Prevalence)

C++ (Undetermined Prevalence)

Likelihood Of Exploit

Low

Demonstrative Examples

Example 1

In this example function, the memory address of variable b is derived by adding 1 to the address of variable a. This derived address is then used to assign the value 0 to b.

(bad code)

Example Language: C

void example() {

char a;
char b;
*(&a + 1) = 0;

}

Here, b may not be one byte past a. It may be one byte in front of a. Or, they may have three bytes between them because they are aligned on 32-bit boundaries.

Detection Methods

Method	Details
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

Method

Details

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

Functional Areas

Memory Management

Affected Resources

Memory

Memberships

Section HelpThis MemberOf Relationships table shows additional CWE Categories and Views that reference this weakness as a member. This information is often useful in understanding where a weakness fits within the context of external information sources.

Nature	Type	ID	Name
MemberOf	CategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.	977	SFP Secondary Cluster: Design
MemberOf	CategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.	1399	Comprehensive Categorization: Memory Safety

Vulnerability Mapping Notes

Usage ALLOWED

(this CWE ID may be used to map to real-world vulnerabilities)

Reason Acceptable-Use

Rationale

This CWE entry is at the Base level of abstraction, which is a preferred level of abstraction for mapping to the root causes of vulnerabilities.

Comments

Carefully read both the name and description to ensure that this mapping is an appropriate fit. Do not try to 'force' a mapping to a lower-level Base/Variant simply to comply with this preferred level of abstraction.

Taxonomy Mappings

Mapped Taxonomy Name	Node ID	Fit	Mapped Node Name
CLASP	Reliance on data layout

References

[REF-62] Mark Dowd, John McDonald and Justin Schuh. "The Art of Software Security Assessment". Chapter 6, "Structure Padding", Page 284. 1st Edition. Addison Wesley. 2006.

[REF-18] Secure Software, Inc.. "The CLASP Application Security Process". 2005.
<https://cwe.mitre.org/documents/sources/TheCLASPApplicationSecurityProcess.pdf>. (URL validated: 2024年11月17日)

Content History

Submissions
Submission Date	Submitter	Organization
2006年07月19日 (CWE Draft 3, 2006年07月19日)	CLASP
2006年07月19日 (CWE Draft 3, 2006年07月19日)
Modifications
Modification Date	Modifier	Organization
2025年09月09日 (CWE 4.18, 2025年09月09日)	CWE Content Team	MITRE
2025年09月09日 (CWE 4.18, 2025年09月09日)	updated Affected_Resources, Functional_Areas
2024年02月29日 (CWE 4.14, 2024年02月29日)	CWE Content Team	MITRE
2024年02月29日 (CWE 4.14, 2024年02月29日)	updated Demonstrative_Examples
2023年06月29日	CWE Content Team	MITRE
2023年06月29日	updated Mapping_Notes
2023年04月27日	CWE Content Team	MITRE
2023年04月27日	updated Detection_Factors, Relationships, Time_of_Introduction
2023年01月31日	CWE Content Team	MITRE
2023年01月31日	updated Description
2021年03月15日	CWE Content Team	MITRE
2021年03月15日	updated References
2019年01月03日	CWE Content Team	MITRE
2019年01月03日	updated Description, Relationships
2014年07月30日	CWE Content Team	MITRE
2014年07月30日	updated Demonstrative_Examples, Relationships
2014年06月23日	CWE Content Team	MITRE
2014年06月23日	updated Description, Other_Notes
2012年10月30日	CWE Content Team	MITRE
2012年10月30日	updated Potential_Mitigations
2012年05月11日	CWE Content Team	MITRE
2012年05月11日	updated References, Relationships
2011年06月01日	CWE Content Team	MITRE
2011年06月01日	updated Common_Consequences
2011年03月29日	CWE Content Team	MITRE
2011年03月29日	updated Common_Consequences
2009年10月29日	CWE Content Team	MITRE
2009年10月29日	updated Common_Consequences
2009年03月10日	CWE Content Team	MITRE
2009年03月10日	updated Relationships
2008年09月08日	CWE Content Team	MITRE
2008年09月08日	updated Applicable_Platforms, Common_Consequences, Relationships, Other_Notes, Taxonomy_Mappings
2008年07月01日	Eric Dalci	Cigital
2008年07月01日	updated Time_of_Introduction
Previous Entry Names
Change Date	Previous Entry Name
2008年04月11日	Reliance on Data Layout

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Page Last Updated: September 09, 2025

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