Univention Corporate Server 4.3 erratum 73 (security)

This update addresses the following issues:
* The TDStretch::processSamples function allows remote attackers to cause a
  denial of service (infinite loop and CPU consumption) via a crafted wav
  file. (CVE-2017-9258)
* The TDStretch::acceptNewOverlapLength function allows remote attackers to
  cause a denial of service (memory allocation error and application crash)
  via a crafted wav file. (CVE-2017-9259)
* The TDStretchSSE::calcCrossCorr function allows remote attackers to cause a
  denial of service (heap-based buffer over-read and application crash) via a
  crafted wav file. (CVE-2017-9260)