Univention Corporate Server 4.2 erratum 367 (security)

This update addresses the following issues:
* Heap-based buffer overflow in the __zzip_get32 function in fetch.c allows
  remote attackers to cause a denial of service (crash) via a crafted ZIP
  file. (CVE-2017-5974)
* Heap-based buffer overflow in the __zzip_get64 function in fetch.c allows
  remote attackers to cause a denial of service (crash) via a crafted ZIP
  file. (CVE-2017-5975)
* Heap-based buffer overflow in the zzip_mem_entry_extra_block function in
  memdisk.c allows remote attackers to cause a denial of service (crash) via
  a crafted ZIP file. (CVE-2017-5976)
* The zzip_mem_entry_new function in memdisk.c allows remote attackers to
  cause a denial of service (out-of-bounds read and crash) via a crafted ZIP
  file. (CVE-2017-5978)
* The prescan_entry function in fseeko.c allows remote attackers to cause a
  denial of service (NULL pointer dereference and crash) via a crafted ZIP
  file. (CVE-2017-5979)
* The zzip_mem_entry_new function in memdisk.c allows remote attackers to
  cause a denial of service (NULL pointer dereference and crash) via a
  crafted ZIP file. (CVE-2017-5980)
* seeko.c allows remote attackers to cause a denial of service (assertion
  failure and crash) via a crafted ZIP file. (CVE-2017-5981)