The source code declares a variable in one scope, but the variable is only used within a narrower scope.
View on MITREThis issue makes it more difficult to understand and/or maintain the product, which indirectly affects security by making it more difficult or time-consuming to find and/or fix vulnerabilities. It also might make it easier to introduce vulnerabilities.
No mitigation information available for this CWE.
No detection method information available for this CWE.
No examples or observed CVEs available for this CWE.
Additional facts reviewed against primary or authoritative security sources.
Documented detection approaches include Automated Static Analysis; recorded impacts include Reduce Maintainability, and Increase Analytical Complexity; related weaknesses include CWE-710. Use these source-defined anchors to turn CWE-1126 into implementation, review, and verification checks for the affected component.
CWE-1126: Declaration of Variable with Unnecessarily Wide Scope — MITRE CWEUse NIST SSDF practices to make prevention of CWE-1126, Declaration of Variable with Unnecessarily Wide Scope, an explicit development outcome. Translate the CWE definition into security requirements and design constraints, choose safer implementation patterns and toolchain checks, and define acceptance evidence before release. Feed every confirmed occurrence back into the requirements, design review, and coding rules so the same root cause is removed across the product rather than patched in one location.
NIST SP 800-218 Secure Software Development Framework — National Institute of Standards and TechnologyUse CISA's Known Exploited Vulnerabilities catalog to test whether a vulnerability mapped to CWE-1126, Declaration of Variable with Unnecessarily Wide Scope, 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 AgencyApply MITRE's full root-cause mapping guidance when using CWE-1126, Declaration of Variable with Unnecessarily Wide Scope. 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 CWEApply MITRE's root-cause mapping quick tips to CWE-1126, Declaration of Variable with Unnecessarily Wide Scope. 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 CWECWE-1126: Declaration of Variable with Unnecessarily Wide Scope is a Common Weakness Enumeration (CWE) entry maintained by MITRE. The source code declares a variable in one scope, but the variable is only used within a narrower scope.
If exploited, CWE-1126 (Declaration of Variable with Unnecessarily Wide Scope) it can compromise Other, leading to outcomes such as Reduce Maintainability and Increase Analytical Complexity.
CWE-1126 commonly affects Not Language-Specific. Note that weaknesses are often language-agnostic patterns, so secure coding practices apply broadly.
A CWE (Common Weakness Enumeration) like CWE-1126 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.