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://security.gentoo.org/glsa/201701-37
https://www.debian.org/security/2016/dsa-3593
http://www.openwall.com/lists/oss-security/2016/01/25/6
http://www.openwall.com/lists/oss-security/2016/01/26/7
http://www.oracle.com/technetwork/topics/security/bulletinjul2016-3090568.html