Univention Corporate Server 4.3 erratum 378 (security)

This update addresses the following issues:
* Memory leak via corrupt td_imagelength in TIFFOpen function
  (CVE-2017-11613)
* Heap-based buffer overflow in tools/pal2rgb.c can lead to denial of service
  (CVE-2017-17095)
* uncontrolled resource consumption in TIFFSetDirectory function in tif_dir.c
  (CVE-2018-5784)
* NULL pointer dereference in tif_print.c:TIFFPrintDirectory() causes a
  denial of service (CVE-2018-7456)
* heap-based buffer overflow in tif_lzw.c:LZWDecodeCompat() allows for denial
  of service (CVE-2018-8905)
* reachable assertion in TIFFWriteDirectorySec function in tif_dirwrite.c
  (CVE-2018-10963)
* Heap-based buffer overflow in ChopUpSingleUncompressedStrip in
  tif_dirread.c (CVE-2018-15209)
* Heap-based buffer overflow in ChopUpSingleUncompressedStrip in
  tif_dirread.c (CVE-2018-16335)
* Two out-of-bounds writes in cpTags in tools/tiff2bw.c and tools/pal2rgb.c
  (CVE-2018-17101)
* Out-of-bounds write in tif_jbig.c (CVE-2018-18557)