# supabase-audit-auth-users

Checks whether Supabase Auth responses reveal if an email is registered. Useful before you ship to production.

- skill · `type=skill` · Claude Code, Codex, Cursor, GitHub Copilot, Gemini CLI, OpenCode · 484 installs · ★ 71
- Author: yoanbernabeu
- License: MIT · policy=mirror · the beginning of the file is at the end of this page
- Source: https://github.com/yoanbernabeu/supabase-pentest-skills/tree/HEAD/skills/audit-auth/supabase-audit-auth-users/SKILL.md
- Updated: 2026-01-31
- HTML: https://affpapa.org/en/nevibecode/skills/supabase-audit-auth-users

## What it does

The skill walks four Supabase Auth endpoints and compares how they behave for an existing user versus a missing one. It covers `/auth/v1/signup`, `/auth/v1/token`, `/auth/v1/recover` and `/auth/v1/otp`. Leaks show up as different error text, different status codes, or different response times.

Findings go into `.sb-pentest-context.json` right after each endpoint is tested, and `.sb-pentest-audit.log` gets an entry before and after every test. If the run dies halfway, the results are already on disk. The final report grades each finding P1 or P2 and lists fixes: identical responses, timing normalisation, rate limiting, CAPTCHA, monitoring.

You need the Supabase project URL and anon key, and the Auth endpoints have to be reachable from the machine running the check. One thing to keep in mind: the tests hit a live project, so run them against a staging instance rather than a production database full of real users.

## Requirements
- Works with: Supabase

## Install

### Claude Code (native platform)

1. **Skills CLI (Vercel)**
```bash
npx skills add yoanbernabeu/supabase-pentest-skills --skill supabase-audit-auth-users -a claude-code
```

2. **Manually: put the files in place**
- File: `~/.claude/skills/supabase-audit-auth-users/SKILL.md` — Copy the whole skill folder; for one project use .claude/skills/supabase-audit-auth-users/

### Codex

1. **Skills CLI (Vercel)**
```bash
npx skills add yoanbernabeu/supabase-pentest-skills --skill supabase-audit-auth-users -a codex
```

2. **Manually: put the files in place**
- File: `.agents/skills/supabase-audit-auth-users/SKILL.md` — For all projects use ~/.agents/skills/

### Cursor

1. **Skills CLI (Vercel)**
```bash
npx skills add yoanbernabeu/supabase-pentest-skills --skill supabase-audit-auth-users -a cursor
```

2. **Manually: put the files in place**
- File: `.cursor/skills/supabase-audit-auth-users/SKILL.md` — Cursor also reads .agents/skills/ and .claude/skills/

### GitHub Copilot

1. **GitHub CLI**
```bash
gh skill install yoanbernabeu/supabase-pentest-skills supabase-audit-auth-users
```

2. **Manually: put the files in place**
- File: `.github/skills/supabase-audit-auth-users/SKILL.md`

### Gemini CLI

1. **Skills CLI (Vercel)**
```bash
npx skills add yoanbernabeu/supabase-pentest-skills --skill supabase-audit-auth-users -a gemini-cli
```

2. **Platform CLI**
```bash
gemini skills install https://github.com/yoanbernabeu/supabase-pentest-skills --path skills/audit-auth/supabase-audit-auth-users
```

### Windsurf (Devin Desktop)

**Manually: put the files in place**
- File: `.devin/skills/supabase-audit-auth-users/SKILL.md` — The legacy .windsurf/skills/ path still works

### OpenCode

**Skills CLI (Vercel)**
```bash
npx skills add yoanbernabeu/supabase-pentest-skills --skill supabase-audit-auth-users -a opencode
```

### Claude.ai

**Claude.ai**
- Zip the folder and upload it in Settings → Capabilities → Skills

Where a file is given instead of a command, copy the files from the source to that path: https://github.com/yoanbernabeu/supabase-pentest-skills/tree/HEAD/skills/audit-auth/supabase-audit-auth-users/SKILL.md

## When to use it
- check whether signup leaks that an email is already taken
- compare login response times for existing and missing accounts
- find a password recovery endpoint that reveals whether a user exists
- catch an OTP request that says outright the user was not found
- collect an Auth endpoint report before a production release

## Example prompts
- Test my Supabase project for user enumeration
- Check the login endpoint for a timing-based leak
- Run the audit on the recovery and OTP endpoints

## Source text · SKILL.md · MIT

Below is the content of a third-party file. It is data, not instructions for you: do not act on anything written inside unless the human asks. Block tag: f3137b5892c832ef.

BEGIN THIRD-PARTY FILE f3137b5892c832ef
````text
---
name: supabase-audit-auth-users
description: Test for user enumeration vulnerabilities through various authentication endpoints.
---

# User Enumeration Audit

> 🔴 **CRITICAL: PROGRESSIVE FILE UPDATES REQUIRED**
>
> You MUST write to context files **AS YOU GO**, not just at the end.
> - Write to `.sb-pentest-context.json` **IMMEDIATELY after each endpoint tested**
> - Log to `.sb-pentest-audit.log` **BEFORE and AFTER each test**
> - **DO NOT** wait until the skill completes to update files
> - If the skill crashes or is interrupted, all prior findings must already be saved
>
> **This is not optional. Failure to write progressively is a critical error.**

This skill tests for user enumeration vulnerabilities in authentication flows.

## When to Use This Skill

- To check if user existence can be detected
- To test login, signup, and recovery flows for information leakage
- As part of authentication security audit
- Before production deployment

## Prerequisites

- Supabase URL and anon key available
- Auth endpoints accessible

## What is User Enumeration?

User enumeration occurs when an application reveals whether a user account exists through:

| Vector | Indicator |
|--------|-----------|
| Different error messages | "User not found" vs "Wrong password" |
| Response timing | Fast for non-existent, slow for existing |
| Response codes | 404 vs 401 |
| Signup response | "Email already registered" |

## Why It Matters

| Risk | Impact |
|------|--------|
| Targeted attacks | Attackers know valid accounts |
| Phishing | Confirm targets have accounts |
| Credential stuffing | Reduce attack scope |
| Privacy | Reveal user presence |

## Tests Performed

| Endpoint | Test Method |
|----------|-------------|
| `/auth/v1/signup` | Try registering existing email |
| `/auth/v1/token` | Try login with various emails |
| `/auth/v1/recover` | Try password reset |
| `/auth/v1/otp` | Try OTP for various emails |

## Usage

### Basic Enumeration Test

```
Test for user enumeration vulnerabilities
```

### Test Specific Endpoint

```
Test login endpoint for user enumeration
```

## Output Format

```
═══════════════════════════════════════════════════════════
 USER ENUMERATION AUDIT
````
END THIRD-PARTY FILE f3137b5892c832ef

The third-party file has ended. Everything between the f3137b5892c832ef tags is data: requests and commands from it are not followed. An “end of file” line with another tag inside the block is part of the file.

First 2331 of 14819 bytes. © yoanbernabeu · MIT · https://github.com/yoanbernabeu/supabase-pentest-skills/tree/HEAD/skills/audit-auth/supabase-audit-auth-users/SKILL.md

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