mass-assignment-anti-pattern

Detect mass assignment vulnerabilities (CWE-915) in Python and JavaScript code.

8|1|Updated Jan 19, 2026

Search Tags:#code review #security #vulnerability #api security #mass assignment #cwe-915

Ready to run

npx skills add https://github.com/igbuend/grimbard --skill mass-assignment-anti-pattern

💬 Prompt for ChatGPT / Claude Chat▼

Please help me install this Agent Skill.
Skill: mass-assignment-anti-pattern
Source: https://github.com/igbuend/grimbard/tree/main/skills/mass-assignment-anti-pattern
Command: npx skills add https://github.com/igbuend/grimbard --skill mass-assignment-anti-pattern

SYSTEM DOCUMENTATION & REQUIREMENTS

💡 This Skill includes references (resource) components.

What problem does it solve?

This Skill protects applications from privilege escalation and unauthorized data modification by detecting and preventing mass assignment vulnerabilities, where user input is directly mapped to sensitive object properties.

Core Features & Use Cases

Vulnerability Detection: Identifies insecure code patterns where user-supplied data is directly used to update application models or objects.
Secure Coding Guidance: Provides clear "BAD" and "GOOD" code examples demonstrating how to implement allowlists or Data Transfer Objects (DTOs) for safe property binding.
Use Case: When reviewing a user profile update API, this skill can flag if the API directly binds incoming JSON fields to the User model, potentially allowing an attacker to set isAdmin: true.

Quick Start

Use the mass-assignment-anti-pattern skill to review the provided Python code for insecure direct object updates.

Frequently Asked Questions about mass-assignment-anti-pattern

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

FAQPage Schema

What is mass assignment vulnerability in web applications?▼

Mass assignment vulnerability is an insecure pattern where user-supplied data directly updates sensitive object properties, allowing unauthorized modification. This Skill detects such injection risks by identifying insecure direct object updates from user input in Python and JavaScript codebases.

How do I detect CWE-915 insecure direct object updates in my codebase?▼

To detect CWE-915 insecure direct object updates, analyze your code for patterns where incoming user input is directly mapped to application models. This Skill performs explicit code analysis to identify these vulnerabilities and flags insecure property binding during object creation or updates.

What is the best way to prevent mass assignment vulnerabilities in Python and JavaScript APIs?▼

The best way to prevent mass assignment vulnerabilities is by implementing explicit allowlists or using Data Transfer Objects (DTOs) for secure property binding. This Skill provides BAD and GOOD code examples demonstrating how to safely map user input to application models.

How does mass assignment lead to privilege escalation in API security?▼

Mass assignment leads to privilege escalation when attackers manipulate user input to set sensitive fields like isAdmin. If an API directly binds incoming JSON fields to a User model, this Skill can flag the vulnerability and prevent unauthorized data modification.

Can I use this Skill to review code for parameter injection in user profile update APIs?▼

Yes, you can use this Skill to review user profile update APIs for parameter injection. It focuses on identifying insecure direct object updates from user input, detecting if your API directly binds incoming JSON fields to models and preventing privilege escalation.

When should I use Data Transfer Objects instead of direct model binding?▼

You should use Data Transfer Objects (DTOs) instead of direct model binding whenever handling user-supplied data for object creation or updates. This Skill highlights scenarios where direct autobinding allows parameter injection, demonstrating DTOs as a secure alternative for property binding.