libvirt before 1.2.12 allow remote authenticated users to obtain the VNC password by using the VIR_DOMAIN_XML_SECURE flag with a crafted (1) snapshot to the virDomainSnapshotGetXMLDesc interface or (2) image to the virDomainSaveImageGetXMLDesc interface.
http://www.ubuntu.com/usn/USN-2867-1
http://security.libvirt.org/2015/0001.html
http://secunia.com/advisories/62766
http://rhn.redhat.com/errata/RHSA-2015-0323.html
http://lists.opensuse.org/opensuse-updates/2015-02/msg00028.html