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

Code Examples & CVEs

Demonstrative Examples

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

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

BadPython

alist = []while (foo()): #now assume there is a string data with a key basenamequeue.append(basename,data)queue.sort()

Source-backed guidance

Additional facts reviewed against primary or authoritative security sources.

Verify controls for CWE-462 with SSDF evidence

Use NIST SSDF verification and vulnerability-response practices to detect CWE-462, Duplicate Key in Associative List (Alist), throughout the product lifecycle. Derive review questions, static or dynamic checks, and negative tests from the CWE's causal behavior; define the components and lifecycle stages each check covers; and retain findings with enough evidence to distinguish the root cause from symptoms and impacts. Track escapes and false negatives, then improve the verification plan after every confirmed occurrence.

NIST SP 800-218 Secure Software Development Framework — National Institute of Standards and Technology

Address Duplicate Key in Associative List (Alist) during Architecture and Design

MITRE associates mitigation with Architecture and Design; recorded impacts include Quality Degradation, and Varies by Context; related weaknesses include CWE-694. Use these source-defined anchors to turn CWE-462 into implementation, review, and verification checks for the affected component.

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

Triage CWE-462 against known exploitation evidence

Use CISA's Known Exploited Vulnerabilities catalog to test whether a vulnerability mapped to CWE-462, Duplicate Key in Associative List (Alist), has evidence of exploitation in the wild. Confirm the CVE-to-CWE root-cause mapping independently before attaching the example, then capture the affected product, required action, and remediation deadline. A missing KEV match is not evidence that the weakness is unexploited, and a KEV entry must not be generalized to every occurrence of this CWE.

Known Exploited Vulnerabilities Catalog — Cybersecurity and Infrastructure Security Agency

Apply precise root-cause mapping to CWE-462

Apply MITRE's full root-cause mapping guidance when using CWE-462, Duplicate Key in Associative List (Alist). Separate weakness language from attacker prerequisites and technical impact, check the entry's abstraction and vulnerability-mapping notes, and prefer the most specific Base or Variant supported by the evidence. Record the rejected alternatives and require an independent review before the mapping is used for remediation trends or program metrics.

CVE to CWE Root Cause Mapping Guidance — MITRE CWE

Validate CWE-462 with root-cause mapping checks

Apply MITRE's root-cause mapping quick tips to CWE-462, Duplicate Key in Associative List (Alist). Confirm the finding describes the causal weakness rather than an impact or attack pattern, compare the abstraction and mapping notes with plausible alternatives, and have a second reviewer challenge the selection. Preserve the evidence and reasoning so recurring defects can be measured against one consistent identifier.

CVE to CWE Root Cause Mapping Quick Tips — MITRE CWE

Frequently Asked Questions

What is CWE-462: Duplicate Key in Associative List (Alist)?+

CWE-462: Duplicate Key in Associative List (Alist) is a Common Weakness Enumeration (CWE) entry maintained by MITRE. Duplicate keys in associative lists can lead to non-unique keys being mistaken for an error. 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.

What are the security consequences of Duplicate Key in Associative List (Alist)?+

If exploited, CWE-462 (Duplicate Key in Associative List (Alist)) it can compromise Other, leading to outcomes such as Quality Degradation and Varies by Context.

How do you prevent or mitigate Duplicate Key in Associative List (Alist)?+

Recommended mitigations for CWE-462 include: Use a hash table instead of an alist. Use an alist which checks the uniqueness of hash keys with each entry before inserting the entry.

Which programming languages are affected by Duplicate Key in Associative List (Alist)?+

CWE-462 commonly affects C, C++, Java and C#. Note that weaknesses are often language-agnostic patterns, so secure coding practices apply broadly.

What is the difference between a CWE and a CVE?+

A CWE (Common Weakness Enumeration) like CWE-462 describes a category of software weakness — the underlying flaw type. A CVE (Common Vulnerabilities and Exposures) identifies a specific, real-world vulnerability in a particular product. In short, a CWE is the kind of mistake, and a CVE is an instance of that mistake being found in software.

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

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