The vulnerability tracked as CVE-2024-4577 is a severe remote code execution flaw found in specific PHP configurations running in CGI (Common Gateway Interface) mode. The issue arises from how PHP improperly handles character encodings in command-line arguments, especially in Windows environments configured with legacy Chinese or Japanese locales. Essentially, an attacker can inject additional command-line options into the PHP CGI process by exploiting a misinterpretation between character encodings and argument parsing—leading to remote code execution (RCE) on the server. This flaw becomes critical when exposed through web servers like Apache or Nginx configured to route requests via PHP-CGI, particularly in shared hosting environments or systems where user input is unsanitized. By crafting a malicious request with special encoded characters (such as %AD or +), attackers can bypass input restrictions and force PHP to execute arbitrary system commands. The impact is worsened if file uploads or user-controlled scripts are enabled, potentially giving threat actors full system access. The best mitigation is disabling PHP-CGI mode entirely if not required, updating to patched PHP versions immediately, and placing strict input validation and WAF rules to block malformed or suspicious queries. This CVE is a strong reminder that character encodings—especially in older systems—can become powerful vectors for modern attacks when coupled with misconfigured execution environments.