CVE-2022-1213: Server side request forgery in LiveHelperChat

The vulnerability stemmed from two key issues in proxycss.php: 1) Direct parsing of user-controlled $_GET parameters without FILTER_VALIDATE_URL validation, and 2) Reliance on parse_url's port/scheme checks without considering URL structure manipulation. The patch added FILTER_VALIDATE_URL checks to both parameters, indicating these were the vulnerable entry points. The pre-patch code's port validation (checking [80,443]) could be bypassed through URLs with embedded ports in the host section (e.g., http://attacker.com:80@evil.com), which parse_url would interpret as port 80 for attacker.com while actually connecting to evil.com on arbitrary ports.