Document Xen Security Advisories (XSAs 167, 168, 170)
Security: CVE-2016-1570
Security: CVE-2016-1571
Security: CVE-2016-2271
Security: https://vuxml.FreeBSD.org/freebsd/7ed7c36f-ddaf-11e5-b2bd-002590263bf5.html
Security: https://vuxml.FreeBSD.org/freebsd/80adc394-ddaf-11e5-b2bd-002590263bf5.html
Security: https://vuxml.FreeBSD.org/freebsd/81f9d6a4-ddaf-11e5-b2bd-002590263bf5.html