Gentoo Linux Security Advisory GLSA 200608-06 – Courier MTA has fixed a security issue relating to usernames containing the = character, causing high CPU utilization. Versions less than 0.53.2 are affected.
You can download this advisory from the following link: https://packetstormsecurity.com/files/download/49042/glsa-200608-06.txt
Source: https://packetstormsecurity.com/files/49042/Gentoo-Linux-Security-Advisory-200608-6.html