A flaw was discovered in the way the kernel allows stackable filesystems to overlay. A local attacker who is able to mount filesystems can abuse this flaw to escalate privileges.
The eCryptfs subsystem in the Linux kernel allows local users to gain privileges via layering a large filesystem stack that includes an overlayfs layer, related to fs/ecryptfs/main.c and fs/overlayfs/super.c.
This issue does not affect the Linux kernel packages as shipped with Red Hat Enterprise Linux 5 and 6.
This issue affects the Linux kernel packages as shipped with Red Hat Enterprise Linux 7, MRG-2. This has been rated as having Moderate security impact and is planned to be addressed in future updates. For additional information, refer to the Red Hat Enterprise Linux Life Cycle: https://access.redhat.com/support/policy/updates/errata/.