PHP can be vulnerable to various security issues, including:
- SQL Injection: Unsanitised user input can lead to unauthorised database access.
- Cross-Site Scripting (XSS): Lack of proper output escaping allows attackers to inject malicious scripts.
- Cross-Site Request Forgery (CSRF): Users can unknowingly perform malicious actions on authenticated sessions.
- File Inclusion Vulnerabilities: Including files based on untrusted data may execute malicious code.
- Insecure File Uploads: Uploading malicious files can lead to code execution on the server.
- Unrestricted URL Access: Direct URL manipulation might grant access to sensitive data or actions.
- Lack of Input Validation: Failing to validate user input can cause unexpected behavior and vulnerabilities.
To enhance security, use prepared statements for SQL queries, sanitise user input before outputting, implement CSRF tokens, validate file uploads, restrict URL access, and validate all user input properly. Regularly updating PHP and following secure coding practices is essential.