testing-api-for-mass-assignment-vulnerability

testing-api-for-mass-assignment-vulnerability is a skill for Claude Code from balsm-health/Balsm-AI. It costs 114 tokens per session (3,848 once invoked), scanned A, original, no licence file.

An API security test for mass assignment, where extra request fields can change protected object properties such as roles, prices, or account balances.

In plain words
What is it for?
Use it during authorized API assessments to identify writable endpoints, add undocumented fields to requests, and check whether the server accepts them.
Why use it?
It helps find endpoints that accept fields clients should not be allowed to edit, which can lead to privilege or data changes.

Skill for Claude Code

Written for Claude Code: shipped in a Claude Code plugin.

Part of the balsm-ai plugin — 66 skills, 1 command, 1 agent, 2 hooks, 3 MCP servers shipped together

Good fit Use it during authorized API assessments to identify writable endpoints, add undocumented fields to requests, and check whether the server accepts them.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/balsm-health/balsm-ai/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 balsm-health/Balsm-AI --skill testing-api-for-mass-assignment-vulnerability
Clone the repo
git clone --depth 1 https://github.com/balsm-health/Balsm-AI

Made for: Claude Code.

Or install balsm-ai, the plugin that ships this one along with the rest of its 66 skills, 1 command, 1 agent, 2 hooks, 3 MCP servers.

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/balsm-health/balsm-ai/testing-api-for-mass-assignment-vulnerability/github.svg)](https://agentmods.dev/skills/balsm-health/balsm-ai/testing-api-for-mass-assignment-vulnerability)
Your own site
<a href="https://agentmods.dev/skills/balsm-health/balsm-ai/testing-api-for-mass-assignment-vulnerability"><img src="https://agentmods.dev/badge/skills/balsm-health/balsm-ai/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/balsm-health/balsm-ai/testing-api-for-mass-assignment-vulnerability"><img src="https://agentmods.dev/badge/skills/balsm-health/balsm-ai/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 3,848 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 $0.03848
Opus 5 $0.00057 $0.01924
Sonnet 5 $0.00023 $0.00770
Haiku 4.5 $0.00011 $0.00385

Measured 8d ago against content hash 1368714ad95c, 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 8d ago.

The scan reads SKILL.md. This mod also ships 1 executable file (scripts/agent.py), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

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()
plugin/skills/testing-api-for-mass-assignment-vulnerability/SKILL.md · 363 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

Files

What ships with it

3 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

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. 8d ago First seen · 363 lines · 114 tokens per session scan A 1368714ad95c

Subscribe to this mod's changes

testing-api-for-mass-assignment-vulnerability is a skill published in the GitHub repository balsm-health/Balsm-AI (2 stars, last pushed 29d ago), with no licence file. It adds 114 tokens to every session and 3,848 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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