# Unchecked Return Value (CWE-252)

The product does not check the return value from a method or function, which can prevent it from detecting unexpected states and conditions.

**Stack:** Go

- Prevalence: 中 2 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 2 件の修正例

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

## Description

When return values are not checked, the program may continue execution in an error state or with incorrect data, potentially leading to security vulnerabilities.

## Prevention

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

### Go

Replace blank identifier _ with err and check error return values

## 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

- 関数の戻り値は常にチェックする
- コンパイラ警告を活用して、未チェックの戻り値を検出する
- エラー状態を適切に処理する

## Detection

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

## Rules by Language

### Go (1 rules)

- **Unchecked Error Return Values** [MEDIUM]: Error return value ignored using blank identifier (_).
  - Remediation: Check all error return values and handle appropriately.

```go
data, err := ioutil.ReadFile(path)
if err != nil {
    return fmt.Errorf("failed to read file: %w", err)
}
```

Learn more: https://shoulder.dev/learn/go/cwe-252/unchecked-errors