dict.c in libxml2 allows remote attackers to cause a denial of service (heap-based buffer over-read and application crash) via an unexpected character immediately after the "<!DOCTYPE html" substring in a crafted HTML document.
https://www.debian.org/security/2016/dsa-3593
https://security.gentoo.org/glsa/201701-37
https://bugzilla.gnome.org/show_bug.cgi?id=749115
http://www.ubuntu.com/usn/USN-2994-1
http://www.securityfocus.com/bid/82071
http://www.oracle.com/technetwork/topics/security/bulletinjul2016-3090568.html