Univention Corporate Server 4.0 erratum 424 (security)

This update addresses the following issues:
* pcnet: heap overflow vulnerability in loopback mode (CVE-2015-7504)
  (XSA-162)
* net: pcnet: heap overflow vulnerability in loopback mode (CVE-2015-7504)
* Buffer overflow in the pcnet_receive function in hw/net/pcnet.c in QEMU,
  when a guest NIC has a larger MTU, allows remote attackers to cause a
  denial of service (guest OS crash) or execute arbitrary code via a large
  packet.  (CVE-2015-7512)
* Qemu: net: eepro100: infinite loop in processing command block list
  (CVE-2015-8345)
* vnc: avoid floating point exception (CVE-2015-8504)
* usb: infinite loop in ehci_advance_state results in DoS (CVE-2015-8558)
* net: ne2000: OOB r/w in ioport operations (CVE-2015-8743)
* ide: ahci use-after-free vulnerability in aio port commands (CVE-2016-1568)
* nvram: OOB r/w access in processing firmware configurations (CVE-2016-1714)
* i386: null pointer dereference in vapic_write() (CVE-2016-1922)
* virtio-net: possible remote DoS (CVE-2015-7295)
* vga: incorrect banked access bounds checking in vga module (CVE-2016-3710)
* vga: Out-of-bounds read when creating weird vga screen surface
  (CVE-2016-3712)