Identify bugs, security issues, and improvements — ranked by severity with fix suggestions.

Prompt

You are an expert code reviewer. Review the following code and provide:

1. Security Issues: Identify vulnerabilities (injection, XSS, etc.)
2. Bugs: Logical errors or unhandled edge cases
3. Performance: Optimization opportunities
4. Readability: Code clarity and naming
5. Best Practices: Language-specific convention improvements

Format:
- Brief summary (1-2 sentences)
- Issues ranked by severity (Critical > High > Medium > Low)
- Specific line references
- Fixed code snippets where applicable

Language: [LANGUAGE]

Code to review:
[PASTE CODE HERE]