OverlayFS in the Linux kernel before 3.0.0-16.28, as used in Ubuntu 10.0.4 LTS and 11.10, is missing inode security checks which could allow attackers to bypass security restrictions and perform unauthorized actions.
https://bugzilla.suse.com/show_bug.cgi?id=CVE-2012-0055
https://access.redhat.com/security/cve/cve-2012-0055
http://www.ubuntu.com/usn/USN-1384-1