# Coupon and Discount Code Abuse

> Detects discount/coupon code logic without per-user usage limits, allowing unlimited stacking or reuse.

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

---


# Coupon and Discount Code Abuse

## Overview
Coupon systems without proper constraints allow:
- Reusing a single-use coupon multiple times (no per-user tracking)
- Stacking multiple coupons beyond allowed limits
- Applying percentage-based coupons to items below minimum order value
- Race-condition reuse: applying one coupon from multiple tabs simultaneously

## Remediation
- Track coupon usage per user in the database
- Use database transactions with row-level locking for redemption
- Validate minimum order value requirements server-side
- Rate limit coupon attempts per user