Canonical Ubuntu Core 15.04

The overlayfs implementation in the Linux kernel through 4.5.2 does not properly restrict the mount namespace, which allows local users to gain privileges by mounting an overlayfs filesystem on top of a FUSE filesystem, and then executing a crafted setuid program.

The overlayfs implementation in the Linux kernel through 4.5.2 does not properly maintain POSIX ACL xattr data, which allows local users to gain privileges by leveraging a group-writable setgid directory.

The do_setup_env function in session.c in sshd in OpenSSH through 7.2p2, when the UseLogin feature is enabled and PAM is configured to read .pam_environment files in user home directories, allows local users to gain privileges by triggering a crafted environment for the /bin/login program, as demonstrated by an LD_PRELOAD environment variable.

An issue was discovered in AppArmor before 2.12. Incorrect handling of unknown AppArmor profiles in AppArmor init scripts, upstart jobs, and/or systemd unit files allows an attacker to possibly have increased attack surfaces of processes that were intended to be confined by AppArmor. This is due to the common logic to handle 'restart' operations removing AppArmor profiles that aren't found in the typical filesystem locations, such as /etc/apparmor.d/. Userspace projects that manage their own AppArmor profiles in atypical directories, such as what's done by LXD and Docker, are affected by this flaw in the AppArmor init script logic.