A denial of service flaw was found in dovecot before 2.2.34 and 2.3.0.1. An attacker able to generate random SNI server names could exploit TLS SNI configuration lookups, leading to excessive memory usage, causing imap-login/pop3-login VSZ limit to be reached and the process restarted. This happens only if Dovecot config has local_name { } or local { } configuration blocks and attacker uses randomly generated SNI servernames.
Vulmon
A denial of service flaw was found in dovecot before 2.2.34 and 2.3.0.1. An attacker able to generate random SNI server names could exploit TLS SNI configuration lookups, leading to excessive memory usage, causing imap-login/pop3-login VSZ limit to be reached and the process restarted. This happens only if Dovecot config has local_name { } or local { } configuration blocks and attacker uses randomly generated SNI servernames.
https://www.dovecot.org/list/dovecot-news/2018-February/000370.html