type-confusion-anti-pattern

Detect type-confusion vulnerabilities (CWE-843) in dynamic-language code with == usage and weak input validation.

8|1|Updated Jan 19, 2026

Search Tags:#security #input validation #type confusion #cwe-843 #loose equality #dynamic languages

Ready to run

npx skills add https://github.com/igbuend/grimbard --skill type-confusion-anti-pattern

💬 Prompt for ChatGPT / Claude Chat▼

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Skill: type-confusion-anti-pattern
Source: https://github.com/igbuend/grimbard/tree/main/skills/type-confusion-anti-pattern
Command: npx skills add https://github.com/igbuend/grimbard --skill type-confusion-anti-pattern

SYSTEM DOCUMENTATION & REQUIREMENTS

💡 This Skill includes references (resource) components.

What problem does it solve?

This Skill helps prevent security vulnerabilities arising from programs misinterpreting data types, which can lead to bypassed security checks or unexpected behavior.

Core Features & Use Cases

Detects Loose Equality Exploits: Identifies instances where == in dynamic languages could be exploited.
Guides Secure Input Handling: Provides best practices for validating data types from external sources like JSON.
Use Case: When reviewing code that handles user-provided IDs or authentication tokens, this skill helps ensure strict type checking is used to prevent attackers from manipulating the system by providing data of an unexpected type.

Quick Start

Review the provided JavaScript code for potential type confusion vulnerabilities.

Frequently Asked Questions about type-confusion-anti-pattern

High-intent search queries and answers about installing and using this skill.

FAQPage Schema

How do I prevent type confusion vulnerabilities when processing JSON user input?▼

Loose equality checks create type confusion vulnerabilities because dynamic languages coerce mismatched types during comparison. Attackers exploit this weak typing behavior to manipulate logic, causing unexpected program behavior or bypassed authentication checks.

What is CWE-843 and how does it relate to dynamic language security?▼

CWE-843 is a type confusion vulnerability where programs misinterpret data types in dynamic languages. It threatens dynamic language security by allowing attackers to bypass security checks or trigger unexpected behavior using improperly validated user input.

How do I fix loose equality exploits in JavaScript authentication logic?▼

To fix loose equality exploits in JavaScript authentication logic, replace `==` operators with strict equality checks and add explicit input validation. This prevents attackers from manipulating authentication tokens through type coercion.

Does this type confusion detection work with weakly typed dynamic languages?▼

Yes, this type confusion detection is designed for weakly typed dynamic languages. It identifies improper input validation and loose equality checks specifically in environments that process JSON or user input using weak typing.

When should I use strict type checking instead of dynamic type comparisons?▼

You should use strict type checking instead of dynamic type comparisons whenever code handles user-provided IDs, authentication tokens, or external JSON. Strict comparisons prevent security vulnerabilities caused by programs misinterpreting data types.