# Variant Analysis

> Finding "variants" of known bugs in other parts of the codebase. Use when this capability is needed.

- Skill: `tomevault-io/variant-analysis-2` (Agent Skill, multi-file: 2 files)
- Install (CLI): `npx skillmds@latest add tomevault-io/variant-analysis-2`
- Raw SKILL.md: https://api.skillmd.com/api/skills/tomevault-io/variant-analysis-2/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: tomevault-io (https://skillmd.com/u/tomevault-io)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/tomevault-io/variant-analysis-2

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# Variant Analysis

This skill helps you multiply the value of a single finding by locating similar vulnerabilities elsewhere.

## 1. The Pivot
Once you find a bug (e.g., "Missing usage of `checked_add` in function A"):
- **Abstract the Pattern**: "Arithmetic operation on user input without checks".
- **Search**: `grep` for other occurrences of the same pattern.

## 2. Common MultiversX Variants
- **Missing Payable Check**:
    - Found: One endpoint accepts payment but doesn't check `call_value()`.
    - Variant Search: Check ALL `#[payable]` endpoints.
- **Unbounded Iteration**:
    - Found: Iterating a `VecMapper` in `compute_reward`.
    - Variant Search: `grep -r "iter()"` on all mappers.
- **Async Callback Revert**:
    - Found: Callback `X` doesn't revert state on failure.
    - Variant Search: Check ALL `#[callback]` functions.

## 3. Automation
- Use `mvx_static_analysis` (Semgrep) to create a temporary rule for the variant.

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> Converted and distributed by [TomeVault](https://tomevault.io/claim/multiversx) — claim your Tome and manage your conversions.
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