# Unchecked Error Condition (CWE-391)

The product does not properly check when a function or operation returns a value that is associated with an error condition.

**Stack:** Python

- Prevalence: 中 3 言語をカバー
- Impact: ハイ 1 件の重大度ハイのルール
- Prevention: 文書化済み 3 件の修正例

**OWASP:** Insecure Design (A04:2021-Insecure Design) - #4

## Description

When error conditions are not checked, the application may continue with invalid or unexpected state, potentially leading to crashes, data corruption, or security vulnerabilities.

## Prevention

1 件の Shoulder 検出ルールに基づく Unchecked Error Condition の予防策。

### Python

Log exceptions or handle them explicitly instead of silently swallowing with pass

## Warning Signs

- [MEDIUM] empty except blocks that silently swallow exceptions

## Consequences

- DoS
- 未承認コードの実行
- アプリケーションデータの変更

## Mitigations

- すべての戻り値とエラー条件をチェックする
- 適切な箇所で例外処理を用いる
- 適切なエラーリカバリ機構を実装する

## Detection

- Total rules: 3
- Languages: go, javascript, typescript, python

## Rules by Language

### Python (1 rules)

- **Empty Exception Handler** [MEDIUM]: Detects empty except blocks that silently swallow exceptions. This can hide
security-critical errors, authentication failures, or data validation issues.
  - Remediation: Log exceptions or handle them explicitly instead of using empty except blocks.

```python
import logging

logger = logging.getLogger(__name__)

try:
    risky_operation()
except Exception as e:
    logger.error(f"Operation failed: {e}", exc_info=True)
    return {'error': 'Operation failed'}, 500
```

Learn more: https://shoulder.dev/learn/python/cwe-391/empty-except