Univention Corporate Server 4.1 erratum 499 (extended maintenance)

This update addresses the following issue:
* Samba is vulnerable to a denial of service attack when the RPC spoolss
  service is configured to be run as an external daemon. Missing input
  sanitization checks on some of the input parameters to spoolss RPC calls
  could cause the print spooler service to crash. There is no known
  vulnerability associated with this error, merely a denial of service.
  If the RPC spoolss service is left by default as an internal service,
  all a client can do is crash its own authenticated connection
  (CVE-2018-1050).
* On a Samba/AD DC the LDAP server incorrectly validates permissions to
  modify passwords over LDAP allowing authenticated users to change any
  other users passwords, including administrative users (CVE-2018-1057).