testing-api-for-mass-assignment-vulnerability

testing-api-for-mass-assignment-vulnerability is a skill for Claude Code, Codex from Njones17/AI-agent-master-cyber-skills-list. It costs 114 tokens per session (3,772 once invoked), scanned A, original, no licence file.

A security test for mass assignment, a flaw where an API accepts extra fields and lets users change properties they should not control. Examples include roles, administrator flags, prices, or account balances.

In plain words
What is it for?
Use it to test writable API endpoints by adding undocumented fields to request bodies and checking whether protected values change.
Why use it?
It helps detect APIs that automatically bind request fields without restricting which properties each user may edit.

Skill for Claude CodeCodex

Which agent this was written for is unclear — body not stored (licence); the path alone says nothing.

Good fit Use it to test writable API endpoints by adding undocumented fields to request bodies and checking whether protected values change.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/njones17/ai-agent-master-cyber-skills-list/testing-api-for-mass-assignment-vulnerability
Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent
npx skills add Njones17/AI-agent-master-cyber-skills-list --skill testing-api-for-mass-assignment-vulnerability
Clone the repo
git clone --depth 1 https://github.com/Njones17/AI-agent-master-cyber-skills-list

Made for: Claude Code, Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for testing-api-for-mass-assignment-vulnerability

README.md
[![agentmods](https://agentmods.dev/badge/skills/njones17/ai-agent-master-cyber-skills-list/testing-api-for-mass-assignment-vulnerability/github.svg)](https://agentmods.dev/skills/njones17/ai-agent-master-cyber-skills-list/testing-api-for-mass-assignment-vulnerability)
Your own site
<a href="https://agentmods.dev/skills/njones17/ai-agent-master-cyber-skills-list/testing-api-for-mass-assignment-vulnerability"><img src="https://agentmods.dev/badge/skills/njones17/ai-agent-master-cyber-skills-list/testing-api-for-mass-assignment-vulnerability/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for testing-api-for-mass-assignment-vulnerability

Your own site · 80×15
<a href="https://agentmods.dev/skills/njones17/ai-agent-master-cyber-skills-list/testing-api-for-mass-assignment-vulnerability"><img src="https://agentmods.dev/badge/skills/njones17/ai-agent-master-cyber-skills-list/testing-api-for-mass-assignment-vulnerability.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 114 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 3,772 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 1 finding. A grade says what 26 rules found in the file — not that it is safe.
Origin unknown No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00114 $0.03772
Opus 5 $0.00057 $0.01886
Sonnet 5 $0.00023 $0.00754
Haiku 4.5 $0.00011 $0.00377

Measured 7d ago against content hash 52e0e3c5cbff, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-11, from the pricing page.

Security

Grade A, and why

testing-api-for-mass-assignment-vulnerability scanned grade A with 1 finding against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 7d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Makes network callslowCapability

Not a fault in itself. Listed so you know the mod talks to something, and to what.

baseline_user = requests.get(f"{BASE_URL}/users/me", headers=user_headers).json()
skills/application-security/testing-api-for-mass-assignment-vulnerability/SKILL.md · 345 lines

The source is not reproduced here

No licence file

A repository with no LICENSE is all rights reserved by default, so the body is not copied here. The metadata, the measurements and the link are.

Read it on GitHub

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 7d ago First seen · 345 lines · 114 tokens per session scan A 52e0e3c5cbff

Subscribe to this mod's changes

testing-api-for-mass-assignment-vulnerability is a skill published in the GitHub repository Njones17/AI-agent-master-cyber-skills-list (21 stars, last pushed 6mo ago), with no licence file. It adds 114 tokens to every session and 3,772 once invoked, about $0.0006 per session on Opus 5. A static security scan graded it A with 1 finding (makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-09-03.

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