The htmlParseNameComplex function in HTMLparser.c in libxml2 allows attackers to cause a denial of service (out-of-bounds read) via a crafted XML document.
https://www.debian.org/security/2016/dsa-3593
https://security.gentoo.org/glsa/201701-37
http://www.ubuntu.com/usn/USN-2994-1
http://www.securitytracker.com/id/1035011
http://www.securityfocus.com/bid/85267
http://www.oracle.com/technetwork/topics/security/bulletinjul2016-3090568.html