It is designed as a faster replacement for Apache and can read many Apache configuration files, including .htaccess rules, which made it easy for hosting companies to adopt. It is common on shared and managed WordPress hosting and in control panels such as cPanel and CyberPanel.
For PHP, LiteSpeed uses LSAPI instead of FastCGI. The PHP programs it starts are called lsphp, and the hosting panel usually installs and manages them. As a customer, you often choose the PHP version in the panel, while the host maintains the packages.
PHP's advisory names LiteSpeed among the affected ways of running PHP. If you are on shared hosting, ask whether your provider has installed the patched PHP version, and check the version your account is using in the control panel. Where you control the server yourself, update the lsphp packages.