Red Hat libvirt 0.2.0 through 0.8.2 creates iptables rules with improper mappings of privileged source ports, which allows guest OS users to bypass intended access restrictions by leveraging IP address and source-port values, as demonstrated by copying and deleting an NFS directory tree.
CVE-2010-2242 libvirt: improperly mapped source privileged ports may allow for obtaining privileged resources on the host
Red Hat would like to thank Jeremy Nickurak for reporting this issue.
Red Hat Security Errata
Red Hat Enterprise Linux Virtualization 5 (libvirt)