The C+ mode offload emulation in the RTL8139 network card device model in QEMU, as used in Xen 4.5.x and earlier, allows remote attackers to read process heap memory via unspecified vectors.
https://www.arista.com/en/support/advisories-notices/security-advisories/1180-security-advisory-13
http://xenbits.xen.org/xsa/advisory-140.html
http://www.securitytracker.com/id/1033176
http://www.securityfocus.com/bid/76153
http://www.oracle.com/technetwork/topics/security/linuxbulletinoct2015-2719645.html
http://www.debian.org/security/2015/dsa-3349
http://www.debian.org/security/2015/dsa-3348
http://rhn.redhat.com/errata/RHSA-2015-1833.html
http://rhn.redhat.com/errata/RHSA-2015-1793.html
http://rhn.redhat.com/errata/RHSA-2015-1740.html
http://rhn.redhat.com/errata/RHSA-2015-1739.html
http://rhn.redhat.com/errata/RHSA-2015-1683.html
http://rhn.redhat.com/errata/RHSA-2015-1674.html
http://lists.opensuse.org/opensuse-security-announce/2015-09/msg00027.html
http://lists.opensuse.org/opensuse-security-announce/2015-08/msg00018.html
http://lists.fedoraproject.org/pipermail/package-announce/2015-September/167820.html
http://lists.fedoraproject.org/pipermail/package-announce/2015-September/167792.html
http://lists.fedoraproject.org/pipermail/package-announce/2015-September/165373.html