# 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: Mittel 3 Sprachen abgedeckt
- Impact: Hoch 1 Regeln mit hohem Schweregrad
- Prevention: Dokumentiert 3 Fix-Beispiele

**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

Präventionsstrategien für Unchecked Error Condition basierend auf 1 Shoulder-Erkennungsregeln.

### 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
- Nicht autorisierten Code ausführen
- Anwendungsdaten ändern

## Mitigations

- Alle Rückgabewerte und Fehlerbedingungen prüfen
- Wo angemessen, Exception-Handling verwenden
- Angemessene Mechanismen zur Fehlerwiederherstellung umsetzen

## 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