Univention Corporate Server 4.1 erratum 495 (extended maintenance)

This update addresses the following issues:
* libclamav/message.c in allows remote attackers to cause a denial of service
  (out-of-bounds read) via a crafted e-mail message. (CVE-2017-6418)
* The wwunpack function in libclamav/wwunpack.c allows remote attackers to
  cause a denial of service (use-after-free) via a crafted PE file with
  WWPack compression. (CVE-2017-6420)
* ClamAV has a use-after-free condition arising from a lack of input
  validation. A remote attacker could exploit this vulnerability with a
  crafted email message to cause a denial of service. (CVE-2017-12374)
* ClamAV has a buffer overflow vulnerability arising from a lack of input
  validation. An unauthenticated remote attacker could send a crafted email
  message to the affected device, triggering a buffer overflow and
  potentially a denial of service when the malicious message is scanned.
  (CVE-2017-12375)
* ClamAV has a buffer overflow vulnerability arising from improper input
  validation when handling Portable Document Format (PDF) files. An
  unauthenticated remote attacker could send a crafted PDF file to the
  affected device, triggering a buffer overflow and potentially a denial of
  service or arbitrary code execution when the malicious file is scanned.
  (CVE-2017-12376)
* ClamAV has a heap overflow vulnerability arising from improper input
  validation when handling mew packets. An attacker could exploit this by
  sending a crafted message to the affected device, triggering a denial of
  service or possible arbitrary code execution when the malicious file is
  scanned. (CVE-2017-12377)
* ClamAV has a buffer overread vulnerability arising from improper input
  validation when handling tape archive (TAR) files. An unauthenticated
  remote attacker could send a crafted TAR file to the affected device,
  triggering a buffer overread and potentially a denial of service when the
  malicious file is scanned. (CVE-2017-12378)
* ClamAV has a buffer overflow vulnerability arising from improper input
  validation in the message parsing function. An unauthenticated remote
  attacker could send a crafted email message to the affected device,
  triggering a buffer overflow and potentially a denial of service or
  arbitrary code execution when the malicious message is scanned.
  (CVE-2017-12379)
* ClamAV has a NULL dereference vulnerability arising from improper input
  validation in the message parsing function. An unauthenticated remote
  attacker could send a crafted email message to the affected device,
  triggering a NULL pointer dereference, which may result in a denial of
  service. (CVE-2017-12380)