An issue was discovered in phpMyAdmin. An unauthenticated user is able to execute a denial-of-service (DoS) attack by forcing persistent connections when phpMyAdmin is running with $cfg['AllowArbitraryServer']=true. All 4.6.x versions (prior to 4.6.4), 4.4.x versions (prior to 4.4.15.8), and 4.0.x versions (prior to 4.0.10.17) are affected.
https://www.phpmyadmin.net/security/PMASA-2016-45
https://security.gentoo.org/glsa/201701-32
https://lists.debian.org/debian-lts-announce/2018/07/msg00006.html