### 🔐 Security
- **CRITICAL**: Fixed command injection vulnerability in DNS record lookup functionality
- **HIGH**: Added comprehensive input validation for all API endpoints
- **HIGH**: Fixed DNS injection vulnerabilities in DMARC, SPF, and WHOIS APIs
- **MEDIUM**: Resolved XSS vulnerabilities in shortcode template files
- **MEDIUM**: Fixed SSRF vulnerability in IP lookup API
- **MEDIUM**: Added validation for blacklist checker API
### 🛡️ Added
- **New Security Functions**:
- `sanitizeDomain()` - Validates and sanitizes domain name inputs
- `sanitizeDnsType()` - Whitelist validation for DNS record types
- `sanitizeDnsServer()` - Validates DNS server IP addresses and hostnames
### 🔧 Changed
- **API Security Improvements**:
- All base64 decoded inputs are now validated before processing
- DNS queries now use sanitized and validated parameters
- External API calls include proper input validation
- Shell commands now use `escapeshellarg()` for parameter escaping
- **Template Security**:
- CSS color values are now properly escaped with `esc_attr()`
- JavaScript variables are sanitized with `esc_js()`
- All user-controlled output is properly escaped
### 🐛 Fixed
- Fixed potential command execution through malicious DNS server parameters
- Resolved XSS vulnerabilities in all shortcode input templates:
- `global-dns-shortcode-input.php`
- `dmarc/global-dns-shortcode-input.php`
- `email_headers/global-dns-shortcode-input.php`
- `blacklist/global-dns-shortcode-input.php`
- `ip_lookup/global-dns-shortcode-input.php`
- `spf_checker/global-dns-shortcode-input.php`
- `whois/global-dns-shortcode-input.php`
- Fixed DNS injection in DMARC record lookups
- Fixed DNS injection in SPF record queries
- Fixed unvalidated IP addresses in blacklist checking
- Improved error handling for invalid input parameters
### 📋 Security Enhancements by API
- **DNS Records API**: Added domain, DNS type, and DNS server validation
- **WHOIS API**: Implemented domain validation for all WHOIS queries
- **IP Lookup API**: Added IP address validation and SSRF protection
- **Domain to IP API**: Added domain validation for hostname resolution
- **Blacklist API**: Added IP and domain validation for blacklist queries
- **DMARC API**: Secured DNS queries with proper domain validation
- **SPF API**: Added input validation for SPF record lookups
### ⚠️ Important Notes
- All changes maintain backward compatibility
- No breaking changes to existing functionality
- Follows WordPress security best practices
- Enhanced protection against OWASP Top 10 vulnerabilities
