# Improper Handling of Unicode Encoding (CWE-176)

The product does not properly handle when an input contains Unicode encoding.

**Stack:** Python

- Prevalence: Średnia Pokryto 3 języków
- Impact: Średni Zalecany przegląd
- Prevention: Udokumentowane 3 przykładów poprawek

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

## Description

Unicode characters can have multiple encodings or representations. If an application does not properly handle Unicode, attackers may be able to bypass security filters or cause unexpected behavior using alternate encodings.

## Prevention

Strategie zapobiegania dla Improper Handling of Unicode oparte na 1 regułach detekcji Shoulder.

### Python

Normalize Unicode strings with NFKC before comparison or security-critical operations

## Warning Signs

- [MEDIUM] missing Unicode normalization leading to security bypasses

## Consequences

- Obejście mechanizmu ochrony
- Wykonanie nieautoryzowanego kodu

## Mitigations

- Normalizuj dane wejściowe Unicode do postaci kanonicznej przed przetwarzaniem
- Kontrole bezpieczeństwa stosuj po normalizacji Unicode
- Stosuj funkcje porównujące świadome Unicode

## Detection

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

## Rules by Language

### Python (1 rules)

- **Unicode Normalization Issues** [MEDIUM]: Detects missing Unicode normalization leading to security bypasses.
  - Remediation: Normalize Unicode strings before comparison using unicodedata.normalize().

```python
import unicodedata

def normalize_username(username):
    return unicodedata.normalize('NFKC', username).lower()

if normalize_username(input_name) == normalize_username(stored_name):
    grant_access()
```

Learn more: https://shoulder.dev/learn/python/cwe-176/unicode-normalization