The remote Debian host is missing a security-related 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 that application to use an excessive amount of CPU, leak potentially sensitive information, or crash the application.
Upgrade the libxml2 packages. For the oldstable distribution (wheezy), these problems have been fixed in version 2.8.0+dfsg1-7+wheezy5. For the stable distribution (jessie), these problems have been fixed in version 2.9.1+dfsg1-5+deb8u1.