# 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: Medium 2 languages covered
- Impact: High 1 high-severity rules
- Prevention: Documented 2 fix examples

**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

Prevention strategies for Unchecked Return Value based on 1 Shoulder detection rules.

### Go

Replace blank identifier _ with err and check error return values

## Consequences

- DoS
- Execute Unauthorized Code
- Modify Application Data

## Mitigations

- Always check return values from functions
- Use compiler warnings to detect unchecked return values
- Handle error conditions appropriately

## 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