When under stress, closing many connections, the HTTP/2 handling code in Apache httpd 2.4.26 would sometimes access memory after it has been freed, resulting in potentially erratic behaviour.
https://support.hpe.com/hpsc/doc/public/display?docLocale=en_US&docId=emr_na-hpesbux03908en_us
https://support.apple.com/HT208221
https://security.netapp.com/advisory/ntap-20170911-0002/
https://security.gentoo.org/glsa/201710-32
https://httpd.apache.org/security/vulnerabilities_24.html