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missing-input-validation-anti-pattern

Detect missing server-side input validation vulnerabilities (CWE-20) in code.

8|1|Updated Jan 19, 2026
Search Tags:#security#input validation#validation#secure coding#anti-pattern#cwe-20
One-click install
npx skills add https://github.com/igbuend/grimbard --skill missing-input-validation-anti-pattern
Or copy as Structured Prompt for Agent▼
Please help me install this Agent Skill.
Skill: missing-input-validation-anti-pattern
Source: https://github.com/igbuend/grimbard/tree/main/skills/missing-input-validation-anti-pattern
Command: npx skills add https://github.com/igbuend/grimbard --skill missing-input-validation-anti-pattern

SYSTEM DOCUMENTATION & REQUIREMENTS

💡 This Skill includes references (resource) components.

What problem does it solve?

This Skill addresses the critical security vulnerability of missing input validation, which is a foundational weakness that enables a wide range of attacks, including SQL Injection, XSS, and Command Injection.

Core Features & Use Cases

  • Detects Vulnerable Code: Identifies instances where user input, form data, API parameters, or external data are not properly validated on the server-side.
  • Promotes Secure Practices: Provides clear "BAD" (vulnerable) and "GOOD" (secure) code examples to illustrate how to implement robust server-side validation.
  • Use Case: When reviewing a web application's user registration form, this skill can help identify if the email address, username, and password fields are being validated for length, format, and allowed characters on the server before being processed, thus preventing common injection attacks.

Quick Start

Review the provided Python Flask code for any missing server-side input validation before processing user-submitted data.

Frequently Asked Questions about missing-input-validation-anti-pattern

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

FAQPage Schema
What is missing input validation and how does it expose web applications to injection attacks?▼

Missing input validation occurs when external data entering an API or web application is not checked on the server-side. This CWE-20 vulnerability enables injection attacks like SQL Injection and XSS by allowing untrusted data to be processed directly.

How do I implement server-side input validation to prevent CWE-20 vulnerabilities?▼

To implement server-side input validation, enforce strict checks on all external data using allowlists. Validate user input, form data, and API parameters for specific type, length, and allowed characters before processing to mitigate injection attacks.

Does my Python Flask API need server-side validation for form data and API parameters?▼

Yes, Python Flask APIs require strict server-side validation for all form data and API parameters. You must validate external data against allowlists for type, length, and format before processing to prevent missing input validation vulnerabilities.

What is the best way to validate external data in APIs to prevent XSS and SQL injection?▼

The best way to validate external data in APIs is enforcing server-side allowlist checks for type, length, and format. This strict validation ensures only properly formatted external data is processed, preventing XSS and SQL injection vulnerabilities.

Why does client-side form validation fail to secure web applications against command injection?▼

Client-side form validation fails because it is easily bypassed by attackers. Securing web applications against command injection requires strict server-side validation of all external data, ensuring untrusted input is checked against allowlists before system processing.

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