# Improper Handling of Extra Parameters (CWE-235)

The product does not handle or incorrectly handles when the number of parameters, fields, or arguments with the same name exceeds the expected amount.

**Stack:** Python

- Prevalence: 中 覆盖 2 种语言
- Impact: 中 建议审查
- Prevention: 已记录 2 个修复示例

**OWASP:** Injection (A03:2021-Injection) - #3

## Description

When applications receive duplicate parameters, they may process them inconsistently, leading to security bypasses or logic errors. Different frameworks may select the first, last, or combine duplicate parameters.

## Prevention

基于 1 条 Shoulder 检测规则的 Improper Handling of Extra Parameters 预防策略。

### Python

Explicitly check for and reject duplicate HTTP parameters

## Warning Signs

- [MEDIUM] handling of duplicate HTTP parameters without proper validation

## Consequences

- 绕过保护机制
- 修改应用程序数据

## Mitigations

- 为处理重复参数定义并执行策略
- 拒绝包含重复的安全敏感参数的请求
- 使用以一致方式处理重复项的框架

## Detection

- Total rules: 2
- Languages: javascript, typescript, python

## Rules by Language

### Python (1 rules)

- **HTTP Parameter Pollution** [MEDIUM]: Detects handling of duplicate HTTP parameters without proper validation.
  - Remediation: Check for duplicate parameters and reject requests with unexpected multiples.

```python
if len(request.args.getlist('param')) > 1:
    return "Duplicate parameters not allowed", 400
```

Learn more: https://shoulder.dev/learn/python/cwe-235/parameter-pollution