From version 2.4.17 (Oct 9, 2015) to version 2.4.38 (Apr 1, 2019), Apache HTTP suffers from a local root privilege escalation vulnerability due to an out-of-bounds array access leading to an arbitrary function call. The vulnerability is triggered when Apache gracefully restarts (apache2ctl graceful). In standard Linux configurations, the logrotate utility runs this command once a day, at 6:25AM, in order to reset log file handles.