Univention Corporate Server 4.2 erratum 592 (extended maintenance)

This update addresses the following issues:
* libavcodec/utils.c omits a certain codec ID during enforcement of
  alignment, which allows remote attackers to cause a denial of service
  (out-of-bounds access) or possibly have unspecified other impact via
  crafted JV data. (CVE-2014-8542)
* Double-free vulnerability in libavformat/mov.c allows remote attackers to
  cause a denial of service (memory corruption and crash) via a crafted .m4a
  file. (CVE-2015-1207)
* FFmpeg has an out-of-bounds write caused by a heap-based buffer overflow
  related to the decode_frame_common function in libavcodec/pngdec.c.
  (CVE-2017-7863)
* FFmpeg has an out-of-bounds write caused by a heap-based buffer overflow
  related to the ipvideo_decode_block_opcode_0xA function in
  libavcodec/interplayvideo.c and the avcodec_align_dimensions2 function in
  libavcodec/utils.c. (CVE-2017-7865)
* In the mxf_read_primer_pack function in libavformat/mxfdec.c an integer
  signedness error might occur when a crafted file, which claims a large
  "item_num" field such as 0xffffffff, is provided. As a result, the variable
  "item_num" turns negative, bypassing the check for a large value.
  (CVE-2017-14169)
* In libavformat/asfdec_f.c, a DoS in asf_build_simple_index() due to lack of
  an EOF (End of File) check might cause huge CPU consumption. When a crafted
  ASF file, which claims a large "ict" field in the header but does not
  contain sufficient backing data, is provided, the for loop would consume
  huge CPU and memory resources, since there is no EOF check inside the loop.
  (CVE-2017-14223)