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.
npx skills add xalgorix/xalgorix --skill testing-api-for-mass-assignment-vulnerabilitygit clone --depth 1 https://github.com/xalgorix/xalgorixWrote 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.
[](https://agentmods.dev/skills/xalgorix/xalgorix/testing-api-for-mass-assignment-vulnerability)<a href="https://agentmods.dev/skills/xalgorix/xalgorix/testing-api-for-mass-assignment-vulnerability"><img src="https://agentmods.dev/badge/skills/xalgorix/xalgorix/testing-api-for-mass-assignment-vulnerability.svg" alt="Measured on agentmods" height="20"></a>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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00114 | $0.04088 |
| Opus 5 | $0.00057 | $0.02044 |
| Sonnet 5 | $0.00023 | $0.00818 |
| Haiku 4.5 | $0.00011 | $0.00409 |
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() How it starts
The opening of the file, as written. The whole thing — 363 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Testing API for Mass Assignment Vulnerability
When to Use
- Testing API endpoints that accept JSON/XML request bodies for user profile updates, registration, or object creation
- Assessing whether the API binds all client-supplied properties to the data model without an allowlist
- Evaluating if users can set privileged attributes (role, permissions, pricing, balance) through regular update endpoints
- Testing APIs built with ORMs that auto-bind request parameters to database models
- Validating that server-side input validation restricts writeable properties per user role
Do not use without written authorization. Mass assignment testing involves modifying object properties in potentially destructive ways.
Most Often Missed & How to Confirm
- Field-name aliasing:
role,is_admin,isAdmin,admin,is_superuser,account_type,roles[]often map to the same column - one spelling failing does not clear the rest. - Domain-specific fields: beyond
role, injectsubscription_plan,credit_limit,balance,discount_percent,verified,is_active, andprice/total. - Nested and framework forms: test
{"user":{"role":"admin"}}, Railsuser[role], Mongoose$set/_id, and Djangois_staff/groups. - Both create and update:
POSTregister andPUT/PATCHprofile may filter differently.
How to confirm a hit (avoid false negatives): a 200 that echoes the injected field is NOT proof - re-fetch the object (GET) and confirm the privileged value persisted, then exercise the privilege (e.g., an admin endpoint returns 200, or an order total is actually charged at 0.01). Don't conclude negative until you've tried: all field-name aliases, nested/framework-specific payloads, both POST and PUT/PATCH, and verified persistence by re-reading the object rather than trusting the write response.
Prerequisites
- Written authorization specifying target API endpoints and scope
- Test accounts at different privilege levels
- API documentation or OpenAPI specification to identify expected request fields
- Burp Suite Professional for request interception and parameter injection
- Python 3.10+ with
requestslibrary - Knowledge of the backend framework (Rails, Django, Express, Spring) to predict parameter binding behavior
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.
- 7d ago First seen · 363 lines · 114 tokens per session scan A 6ef704bfb735
testing-api-for-mass-assignment-vulnerability is a skill published in the GitHub repository xalgorix/xalgorix (959 stars, last pushed today), licensed Apache-2.0. It adds 114 tokens to every session and 4,088 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 2026-08-30.
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