The Smart Slider 3 WordPress plugin before 3.5.1.11 unserialises the content of an imported file, which could lead to PHP object injection issues when a user import (intentionally or not) a malicious file, and a suitable gadget chain is present on the site.
The overlayfs implementation in the linux kernel did not properly validate with respect to user namespaces the setting of file capabilities on files in an underlying file system. Due to the combination of unprivileged user namespaces along with a patch carried in the Ubuntu kernel to allow unprivileged overlay mounts, an attacker could use this to gain elevated privileges.