Univention Corporate Server 4.3 erratum 667 (extended maintenance)

This update addresses the following issue:
 * With a crafted URL that contains a newline, the credential
   helper machinery can be fooled to supply credential information
   for the wrong host.  The attack has been made impossible by
   forbidding a newline character in any value passed via the
   credential protocol. (CVE-2020-5260)