This is a memory corruption vulnerability in the Apache Scoreboard , a shared memory area used by the main process (running as root) to track child processes (running with low privileges like www-data ).
The following article details the primary vulnerabilities, how they are exploited, and how to secure your environment. apache httpd 2.4.18 exploit
A malicious script (e.g., PHP or CGI) running with low privileges can modify the scoreboard to point to a malicious function. When the Apache server undergoes a graceful restart —typically triggered daily by automated tasks like logrotate —the parent root process executes the malicious code, granting the attacker full root access to the server. Impact: Complete server takeover. 2. HTTP/2 Denial of Service (CVE-2016-1546) This is a memory corruption vulnerability in the