The slirp_smb function in net/slirp.c in QEMU 2.3.0 and earlier creates temporary files with predictable names, which allows local users to cause a denial of service (instantiation failure) by creating /tmp/qemu-smb.*-* files before the program.
https://bugzilla.redhat.com/show_bug.cgi?id=1222892
http://www.ubuntu.com/usn/USN-2630-1
http://www.securitytracker.com/id/1032547
http://www.securityfocus.com/bid/74809
http://www.openwall.com/lists/oss-security/2015/05/23/4
http://www.openwall.com/lists/oss-security/2015/05/16/5
http://www.openwall.com/lists/oss-security/2015/05/13/7
http://www.debian.org/security/2015/dsa-3285
http://www.debian.org/security/2015/dsa-3284
http://lists.opensuse.org/opensuse-updates/2015-11/msg00063.html
http://lists.opensuse.org/opensuse-security-announce/2015-09/msg00015.html
http://lists.opensuse.org/opensuse-security-announce/2015-06/msg00027.html
http://lists.fedoraproject.org/pipermail/package-announce/2015-June/160414.html
http://lists.fedoraproject.org/pipermail/package-announce/2015-June/160058.html