Canonical Apologizes for Linux Kernel Regression in Ubuntu, Patch Released

It would appear that the Linux kernel update released on June 15, 2015, which was supposed to patch the CVE-2015-1328 bug related to a privilege escalation when using OverlayFS mounts inside of user namespaces, introduced a regression. The regression was introduced into the Linux kernel’s OverlayFS filesystem and it could create a kernel panic by removing the directory that existed only on the lower layer.