CWE-1109: Use of Same Variable for Multiple Purposes

Source-backed guidance

Additional facts reviewed against primary or authoritative security sources.

Verify controls for CWE-1109 with SSDF evidence

Use NIST SSDF verification and vulnerability-response practices to detect CWE-1109, Use of Same Variable for Multiple Purposes, 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

Make elimination of CWE-1109 a product outcome

Apply CISA's Secure by Design principle of taking ownership of customer security outcomes to CWE-1109, Use of Same Variable for Multiple Purposes. Put the weakness in the product threat model and security roadmap, fund class-level design and platform changes, prefer safe defaults and reusable guardrails, and publish measurable progress. Do not transfer the primary burden to customer configuration when the manufacturer can remove or contain the root cause in the product.

Shifting the Balance of Cybersecurity Risk: Secure by Design Software — Cybersecurity and Infrastructure Security Agency

Connect Use of Same Variable for Multiple Purposes to documented attack evidence

Recorded impacts include Reduce Maintainability, and Increase Analytical Complexity; observed examples include CVE-2023-26463; related weaknesses include CWE-1078. Use these source-defined anchors to turn CWE-1109 into implementation, review, and verification checks for the affected component.

CWE-1109: Use of Same Variable for Multiple Purposes — MITRE CWE

Apply precise root-cause mapping to CWE-1109

Apply MITRE's full root-cause mapping guidance when using CWE-1109, Use of Same Variable for Multiple Purposes. 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-1109 with root-cause mapping checks

Apply MITRE's root-cause mapping quick tips to CWE-1109, Use of Same Variable for Multiple Purposes. 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-1109: Use of Same Variable for Multiple Purposes?+

CWE-1109: Use of Same Variable for Multiple Purposes is a Common Weakness Enumeration (CWE) entry maintained by MITRE. The code contains a callable, block, or other code element in which the same variable is used to control more than one unique task or store more than one instance of data.

What are the security consequences of Use of Same Variable for Multiple Purposes?+

If exploited, CWE-1109 (Use of Same Variable for Multiple Purposes) it can compromise Other, leading to outcomes such as Reduce Maintainability and Increase Analytical Complexity.

Which programming languages are affected by Use of Same Variable for Multiple Purposes?+

CWE-1109 commonly affects Not Language-Specific. Note that weaknesses are often language-agnostic patterns, so secure coding practices apply broadly.

What are real-world examples of Use of Same Variable for Multiple Purposes?+

MITRE documents real CVEs mapped to CWE-1109, including CVE-2023-26463. You can look up the full details of each CVE, including CVSS scores and remediation guidance, on our CVE Lookup tool.

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

A CWE (Common Weakness Enumeration) like CWE-1109 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-1109: Use of Same Variable for Multiple Purposes

Technical Details

Applicable To

Security Consequences

Scope

Impact

Scope

Impact

Mitigation Strategies

Detection Methods

Code Examples & CVEs

Observed CVE Examples (1)

CWE Relationships

Parent Weaknesses