Security update for libxml2

Open Source Vulnerabilities SUSE-SU-2018:3081-1

This update for libxml2 fixes the following security issues: - CVE-2018-9251: The xz_decomp function allowed remote attackers to cause a denial of service (infinite loop) via a crafted XML file that triggers LZMA_MEMLIMIT_ERROR, as demonstrated by xmllint (bsc#1088279). - CVE-2018-14567: Prevent denial of service (infinite loop) via a crafted XML file that triggers LZMA_MEMLIMIT_ERROR, as demonstrated by xmllint (bsc#1105166). - CVE-2018-14404: Prevent NULL pointer dereference in the xmlXPathCompOpEval() function when parsing an invalid XPath expression in the XPATH_OP_AND or XPATH_OP_OR case leading to a denial of service attack (bsc#1102046). - CVE-2017-18258: The xz_head function allowed remote attackers to cause a denial of service (memory consumption) via a crafted LZMA file, because the decoder functionality did not restrict memory usage to what is required for a legitimate file (bsc#1088601).