mod_php is an Apache module that runs PHP code inside the web server’s own process. When Apache receives a request for a PHP page, the module passes the script to the PHP runtime and returns the generated response.
This setup can make deployment straightforward, but it also means PHP vulnerabilities may put the Apache-serving environment at risk. In real attacks, a flaw in an exposed PHP runtime could let an attacker execute code through a web request. Defenders should inventory where mod_php is enabled, update PHP promptly, and restart or reload Apache so the patched runtime is active. Other deployments, such as PHP-FPM, use separate worker processes and require their own update and verification steps.