The buffer_slow_realign function in HAProxy 1.5.x before 1.5.14 and 1.6-dev does not properly realign a buffer that is used for pending outgoing data, which allows remote attackers to obtain sensitive information (uninitialized memory contents of previous requests) via a crafted request.
http://git.haproxy.org/?p=haproxy-1.5.git;a=commit;h=7ec765568883b2d4e5a2796adbeb492a22ec9bd4
http://lists.opensuse.org/opensuse-security-announce/2015-10/msg00001.html
http://lists.opensuse.org/opensuse-security-announce/2015-10/msg00023.html
http://rhn.redhat.com/errata/RHSA-2015-1741.html
http://rhn.redhat.com/errata/RHSA-2015-2666.html
http://www.debian.org/security/2015/dsa-3301
http://www.haproxy.org/news.html