I have the same problem with the same Debian and Apache2 version (upgrade testing/buster 2018/07/07):
/var/log/kern.log: Jul 9 18:25:28 eussa kernel: [12436.633037] /usr/sbin/apach[12386]: segfault at 7f5c82d98660 ip 00007f5c82d98660 sp 00007ffcfaf711f8 error 14 in libcap-ng.so.0.0.0[7f5c82d70000+200000] Jul 9 18:25:28 eussa kernel: [12436.708687] /usr/sbin/apach[12387]: segfault at 7f5c82d98660 ip 00007f5c82d98660 sp 00007ffcfaf72628 error 14 in libcap-ng.so.0.0.0[7f5c82d70000+200000] But for me, the culprit was "nscd", if i start or restart apache2 with service "nscd" started, i have a segfault. If i stop "nscd", apache2 start normaly and after i can start "nscd". But after a new "apache2 restart" produce a segfault. ii apache2 2.4.33-3+b1 ii apache2-bin 2.4.33-3+b1 ii apache2-data 2.4.33-3 ii apache2-dev 2.4.33-3+b1 ii apache2-doc 2.4.33-3 ii apache2-utils 2.4.33-3+b1 ii libapache2-mod-apreq2 2.13-5+b2 ii libapache2-mod-authnz-pam 1.1.0-1 ii libapache2-mod-perl2 2.0.10-2+b1 ii libapache2-reload-perl 0.13-1 ii libapache2-request-perl 2.13-5+b2 ii nscd 2.27-3 # apachectl -M Loaded Modules: core_module (static) so_module (static) watchdog_module (static) http_module (static) log_config_module (static) logio_module (static) version_module (static) unixd_module (static) alias_module (shared) apreq_module (shared) auth_basic_module (shared) authn_core_module (shared) authn_file_module (shared) authnz_pam_module (shared) authz_core_module (shared) authz_host_module (shared) authz_user_module (shared) autoindex_module (shared) cgid_module (shared) deflate_module (shared) dir_module (shared) env_module (shared) filter_module (shared) include_module (shared) mime_module (shared) mpm_event_module (shared) negotiation_module (shared) perl_module (shared) reqtimeout_module (shared) setenvif_module (shared) status_module (shared) unique_id_module (shared) userdir_module (shared) -- +-----------------------------------------------------------------------+ . Mèl. bruno pomar à aviation-civile gouv fr . Tél. +33 (0)2 98 37 32 65 --- Fax. +33 (0)2 98 37 35 04 . CRNA Ouest, Service T, Subdivision QI