Individual skill

api-mass-assignment

Mass assignment / auto-binding privilege escalation. Load when an API binds JSON directly to a model (Rails, Spring, Django REST, Node/Mongoose), on signup/profile-update/create endpoints, or when responses expose fields you didn't send (role, isAdmin, balance, verified). Signals: ORM object binding, extra fields accepted silently.

skills/api/api-mass-assignment/SKILL.md

Read pinned source

Source commit ee0e0c50d2f6d941a14b73dd85a2b470d0ab976e

What was checked

Matches the observed repository HEAD: Yes
Scanner rules are current: No
Repository scan complete: No
Skill scan complete: Yes
Observed behavior: Not checked yet
Last checked: Nov 7, 2026

These are observations at the recorded commit, not a guarantee of safety. Review the source before running it.

Install this skill

Choose an agent in your Stack or copy a command below. Commands fetch the pinned commit and copy only this skill directory. Existing destinations are refused. Copying a command does not install anything.

An install command is unavailable: current rules, complete repository and skill scans, an eligible behavior level and a permitted license are required.

Repository context

Repository stars (not skill ratings): 27
Repository last updated: Oct 14, 2026
License: MIT

Observed agent integration: No specific integration evidence. Standard SKILL.md installation does not imply verified compatibility.

agent-skills Repository topic
ai-agents Repository topic
ai-security Repository topic
application-security Repository topic
blue-team Repository topic
bug-bounty Repository topic
claude-code Repository topic
codex Repository topic
detection-engineering Repository topic
gemini Repository topic
engineering Derived category
engineering-web Derived category

Files and excerpt

File metadata and permitted, redacted excerpts come from the recorded scan. Source links are pinned to that commit.

Browse files

SKILL.mdcore · 2,346 bytes
detection.mddoc · 3,057 bytes

Read excerpt


# Mass assignment (BOPLA)

## When it applies
An endpoint deserializes client JSON straight into a data object without an allowlist of
writable fields. You add sensitive properties the developer never meant to be client-writable.

## Why it works
Frameworks that auto-bind request bodies to models will set *any* matching attribute unless
explicitly restricted. If `role`, `isAdmin`, `account_balance`, `email_verified`, or
`user_id` are bindable, you set them by just including them in the body.

## Method
1. **Learn the object shape**: read a GET response for the object — every returned field is a
   candidate writable property. Also mine JS, mobile apps, and API docs for hidden fields.