CWE - CWE-462: Duplicate Key in Associative List (Alist) (4.18)

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CWE Glossary Definition

CWE-462: Duplicate Key in Associative List (Alist)

Weakness ID: 462

Vulnerability Mapping: ALLOWED This CWE ID may be used to map to real-world vulnerabilities
Abstraction: 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.

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Description

Duplicate keys in associative lists can lead to non-unique keys being mistaken for an error.

Extended Description

A duplicate key entry -- if the alist is designed properly -- could be used as a constant time replace function. However, duplicate key entries could be inserted by mistake. Because of this ambiguity, duplicate key entries in an association list are not recommended and should not be allowed.

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
Quality Degradation; Varies by Context	Scope: Other

Potential Mitigations

Phase(s)	Mitigation
Architecture and Design	Use a hash table instead of an alist.
Architecture and Design	Use an alist which checks the uniqueness of hash keys with each entry before inserting the entry.

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	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.	694	Use of Multiple Resources with Duplicate Identifier

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)

Java (Undetermined Prevalence)

C# (Undetermined Prevalence)

Likelihood Of Exploit

Low

Demonstrative Examples

Example 1

The following code adds data to a list and then attempts to sort the data.

(bad code)

Example Language: Python

alist = []
while (foo()): #now assume there is a string data with a key basename

queue.append(basename,data)
queue.sort()

Since basename is not necessarily unique, this may not sort how one would like it to be.

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.	744	CERT C Secure Coding Standard (2008) Chapter 11 - Environment (ENV)
MemberOf	CategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.	878	CERT C++ Secure Coding Section 10 - Environment (ENV)
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.	1412	Comprehensive Categorization: Poor Coding Practices

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 Variant 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	Duplicate key in associative list (alist)
CERT C Secure Coding	ENV02-C	Beware of multiple environment variables with the same effective name

References

[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
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 Relationships, Time_of_Introduction, Type
2020年02月24日	CWE Content Team	MITRE
2020年02月24日	updated References, Relationships
2017年11月08日	CWE Content Team	MITRE
2017年11月08日	updated Taxonomy_Mappings
2014年07月30日	CWE Content Team	MITRE
2014年07月30日	updated Relationships
2012年05月11日	CWE Content Team	MITRE
2012年05月11日	updated Relationships
2011年09月13日	CWE Content Team	MITRE
2011年09月13日	updated Relationships, Taxonomy_Mappings
2011年06月27日	CWE Content Team	MITRE
2011年06月27日	updated Common_Consequences
2011年06月01日	CWE Content Team	MITRE
2011年06月01日	updated Common_Consequences
2009年10月29日	CWE Content Team	MITRE
2009年10月29日	updated Demonstrative_Examples, Description, Other_Notes
2008年11月24日	CWE Content Team	MITRE
2008年11月24日	updated Relationships, Taxonomy_Mappings
2008年09月08日	CWE Content Team	MITRE
2008年09月08日	updated Applicable_Platforms, Relationships, Other_Notes, Taxonomy_Mappings
2008年07月01日	Eric Dalci	Cigital
2008年07月01日	updated Time_of_Introduction

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Page Last Updated: September 09, 2025

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