HAproxy 1.6.x before 1.6.6, when a deny comes from a reqdeny rule, allows remote attackers to cause a denial of service (uninitialized memory access and crash) or possibly have unspecified other impact via unknown vectors.
http://www.ubuntu.com/usn/USN-3011-1
http://www.openwall.com/lists/oss-security/2016/06/09/6
http://www.openwall.com/lists/oss-security/2016/06/09/5
http://git.haproxy.org/?p=haproxy-1.6.git%3Ba=commit%3Bh=60f01f8c89e4fb2723d5a9f2046286e699567e0b