The tcp_request function in Dnsmasq before 2.73rc4 does not properly handle the return value of the setup_reply function, which allows remote attackers to read process memory and cause a denial of service (out-of-bounds read and crash) via a malformed DNS request.
https://security.gentoo.org/glsa/201512-01
http://www.ubuntu.com/usn/USN-2593-1
http://www.securitytracker.com/id/1032195
http://www.securityfocus.com/bid/74452
http://www.securityfocus.com/archive/1/535354/100/1100/threaded
http://www.oracle.com/technetwork/topics/security/bulletinjul2015-2511963.html
http://www.debian.org/security/2015/dsa-3251
http://lists.thekelleys.org.uk/pipermail/dnsmasq-discuss/2015q2/009387.html
http://lists.opensuse.org/opensuse-updates/2015-05/msg00013.html