# BadRequest: 400 Bad Request: The CSRF token is missing.

- **ID:** `python/flask-csrf-token-missing`
- **Domain:** python
- **Category:** auth_error
- **Verification:** ai_generated
- **Fix Rate:** 80%

## Root Cause

Flask-WTF 表单提交时未包含 CSRF 令牌。

## Version Compatibility

| Version | Status | Introduced | Deprecated |
|---------|--------|------------|------------|
| 3.x | active | — | — |

## Workarounds

1. **** (95% success)
   ```
   <form method='post'>\n    <input type='hidden' name='csrf_token' value='{{ csrf_token() }}'>\n</form>
   ```
2. **** (90% success)
   ```
   from flask_wtf.csrf import CSRFProtect\ncsrf = CSRFProtect(app)
   ```

## Dead Ends

- **** — 降低安全性，易受攻击。 (90% fail)
- **** — 字段名不匹配，仍会失败。 (70% fail)