virt-edit in libguestfs before 1.18.0 does not preserve the permissions from the original file and saves the new file with world-readable permissions when editing, which might allow local guest users to obtain sensitive information.
https://www.redhat.com/archives/libguestfs/2012-May/msg00104.html
https://exchange.xforce.ibmcloud.com/vulnerabilities/76220
http://www.securityfocus.com/bid/53932
http://secunia.com/advisories/49545