[wellylug] Major Ubuntu Linux Vulnerability - all current versions

[Mark Foster]

http://seclists.org/oss-sec/2015/q2/717

... "allows a local root privilege escalation in the default 
configuration on all currently supported versions of Ubuntu. The 
overlayfs filesystem does not correctly check file permissions when 
creating new files in the upper filesystem directory. This can be 
exploited by an unprivileged process in kernels with CONFIG_USER_NS=y 
and where overlayfs has the FS_USERNS_MOUNT flag, which allows the 
mounting of overlayfs inside unprivileged mount namespaces. This is the 
default configuration of Ubuntu 12.04, 14.04, 14.10, and 15.04 [1]."

This could be something requiring a bit of attention. Heads-up.
There is a simple work-round if you're not using overlayfs, detailed at 
the above url.

Mark.

PS: Apol's for the cross-post.