Univention Corporate Server 4.2 erratum 300 (security)

This update addresses the following issues:
* Integer overflow in the jpc_dec_tiledecode function in jpc_dec.c allows
  remote attackers to have unspecified impact via a crafted image file, which
  triggers a heap-based buffer overflow. (CVE-2016-10249)
* Integer overflow in the jpc_pi_nextcprl function in jpc_t2cod.c allows
  remote attackers to have unspecified impact via a crafted file, which
  triggers use of an uninitialized value. (CVE-2016-10251)
* Use-after-free on heap in jas_matrix_destroy (CVE-2016-9591)