CWE-837: Improper Enforcement of a Single, Unique Action

Extended Description

In various applications, a user is only expected to perform a certain action once, such as voting, requesting a refund, or making a purchase. When this restriction is not enforced, sometimes this can have security implications. For example, in a voting application, an attacker could attempt to "stuff the ballot box" by voting multiple times. If these votes are counted separately, then the attacker could directly affect who wins the vote. This could have significant business impact depending on the purpose of the product.

Source-backed guidance

Additional facts reviewed against primary or authoritative security sources.

Verify controls for CWE-837 with SSDF evidence

Use NIST SSDF verification and vulnerability-response practices to detect CWE-837, Improper Enforcement of a Single, Unique Action, 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-837 a product outcome

Apply CISA's Secure by Design principle of taking ownership of customer security outcomes to CWE-837, Improper Enforcement of a Single, Unique Action. 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 Improper Enforcement of a Single, Unique Action to documented attack evidence

Recorded impacts include Varies by Context; observed examples include CVE-2008-0294, CVE-2005-4051, and CVE-2002-216; related weaknesses include CWE-799. Use these source-defined anchors to turn CWE-837 into implementation, review, and verification checks for the affected component.

CWE-837: Improper Enforcement of a Single, Unique Action — MITRE CWE

Apply precise root-cause mapping to CWE-837

Apply MITRE's full root-cause mapping guidance when using CWE-837, Improper Enforcement of a Single, Unique Action. 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-837 with root-cause mapping checks

Apply MITRE's root-cause mapping quick tips to CWE-837, Improper Enforcement of a Single, Unique Action. 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-837: Improper Enforcement of a Single, Unique Action?+

CWE-837: Improper Enforcement of a Single, Unique Action is a Common Weakness Enumeration (CWE) entry maintained by MITRE. The product requires that an actor should only be able to perform an action once, or to have only one unique action, but the product does not enforce or improperly enforces this restriction. In various applications, a user is only expected to perform a certain action once, such as voting, requesting a refund, or making a purchase. When this restriction is not enforced, sometimes this can have security implications. For example, in a voting application, an attacker could attempt to "stuff the ballot box" by voting multiple times. If these votes are counted separately, then the attacker could directly affect who wins the vote. This could have significant business impact depending on the purpose of the product.

What are the security consequences of Improper Enforcement of a Single, Unique Action?+

If exploited, CWE-837 (Improper Enforcement of a Single, Unique Action) it can compromise Other, leading to outcomes such as Varies by Context.

Which programming languages are affected by Improper Enforcement of a Single, Unique Action?+

CWE-837 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 Improper Enforcement of a Single, Unique Action?+

MITRE documents real CVEs mapped to CWE-837, including CVE-2008-0294, CVE-2005-4051, CVE-2002-216, CVE-2003-1433 and CVE-2002-1018. 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-837 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-837: Improper Enforcement of a Single, Unique Action

Extended Description

Technical Details

Applicable To

Security Consequences

Scope

Impact

Mitigation Strategies

Detection Methods

Code Examples & CVEs

Observed CVE Examples (6)

CWE Relationships

Parent Weaknesses