libxml2 - security update

Several vulnerabilities were discovered in libxml2, a library providing
support to read, modify and write XML and HTML files. A remote attacker
could provide a specially crafted XML or HTML file that, when processed
by an application using libxml2, would cause a denial-of-service against
the application, or potentially, the execution of arbitrary code with
the privileges of the user running the application.

For the stable distribution (jessie), these problems have been fixed in
version 2.9.1+dfsg1-5+deb8u4.

For the testing distribution (stretch), these problems have been fixed
in version 2.9.4+dfsg1-2.1.

For the unstable distribution (sid), these problems have been fixed in
version 2.9.4+dfsg1-2.1.

We recommend that you upgrade your libxml2 packages.