Univention Corporate Server 4.2 erratum 517 (security)

This update addresses the following issues:
* status command permitted with -dSAFER in psi/zfile.c allowing attackers to
  identify the size and existence of files (CVE-2018-11645)
* .tempfile file permission issues (CVE-2018-15908)
* shading_param incomplete type checking (CVE-2018-15909)
* LockDistillerParams type confusion (CVE-2018-15910)
* uninitialized memory access in the aesdecode operator (CVE-2018-15911)
* /invalidaccess bypass after failed restore (CVE-2018-16509)
* missing type check in type checker (CVE-2018-16511)
* setcolor missing type check (CVE-2018-16513)
* incorrect access checking in temp file handling to disclose contents of
  files (CVE-2018-16539)
* use-after-free in copydevice handling (CVE-2018-16540)
* incorrect free logic in pagedevice replacement (CVE-2018-16541)
* .definemodifiedfont memory corruption if /typecheck is handled
  (CVE-2018-16542)
* .setdistillerkeys PostScript command is accepted even though it is not
  intended for use (CVE-2018-16585)
* Incorrect "restoration of privilege" checking when running out of stack
  during exception handling (CVE-2018-16802)