Univention Corporate Server 4.2 erratum 329 (security)

This update addresses the following issues:
* An abort of SASL authentication results in a memory leak in dovecot's auth
  client used by login processes. The leak has impact in high performance
  configuration where same login processes are reused and can cause the
  process to crash due to memory exhaustion. (CVE-2017-15132)
* A specially crafted email delivered over SMTP and passed on to Dovecot by
  MTA can trigger an out of bounds read resulting in potential sensitive
  information disclosure and denial of service. In order to trigger this
  vulnerability, an attacker needs to send a specially crafted email message
  to the server. (CVE-2017-14461)
* An attacker able to generate random SNI server names could exploit TLS SNI
  configuration lookups, leading to excessive memory usage and the process to
  restart. (CVE-2017-15130)