A feature in LXD (LP#1829071), affects the default configuration of Ubuntu Server which allows privileged users in the lxd group to escalate their privilege to root without requiring a sudo password.
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.
Shiftfs, an out-of-tree stacking file system included in Ubuntu Linux kernels, did not properly handle faults occurring during copy_from_user() correctly. These could lead to either a double-free situation or memory not being freed at all. An attacker could use this to cause a denial of service (kernel memory exhaustion) or gain privileges via executing arbitrary code. AKA ZDI-CAN-13562.
Apport reads and writes information on a crashed process to /proc/pid with elevated privileges. Apport then determines which user the crashed process belongs to by reading /proc/pid through get_pid_info() in data/apport. An unprivileged user could exploit this to read information about a privileged running process by exploiting PID recycling. This information could then be used to obtain ASLR offsets for a process with an existing memory corruption vulnerability. The initial fix introduced regressions in the Python Apport library due to a missing argument in Report.add_proc_environ in apport/report.py. It also caused an autopkgtest failure when reading /proc/pid and with Python 2 compatibility by reading /proc maps. The initial and subsequent regression fixes are in 2.20.11-0ubuntu16, 2.20.11-0ubuntu8.6, 2.20.9-0ubuntu7.12, 2.20.1-0ubuntu2.22 and 2.14.1-0ubuntu3.29+esm3.
In shiftfs, a non-upstream patch to the Linux kernel included in the Ubuntu 5.0 and 5.3 kernel series, shiftfs_btrfs_ioctl_fd_replace() installs an fd referencing a file from the lower filesystem without taking an additional reference to that file. After the btrfs ioctl completes this fd is closed, which then puts a reference to that file, leading to a refcount underflow.
In shiftfs, a non-upstream patch to the Linux kernel included in the Ubuntu 5.0 and 5.3 kernel series, shiftfs_btrfs_ioctl_fd_replace() calls fdget(oldfd), then without further checks passes the resulting file* into shiftfs_real_fdget(), which casts file->private_data, a void* that points to a filesystem-dependent type, to a "struct shiftfs_file_info *". As the private_data is not required to be a pointer, an attacker can use this to cause a denial of service or possibly execute arbitrary code.
In shiftfs, a non-upstream patch to the Linux kernel included in the Ubuntu 5.0 and 5.3 kernel series, several locations which shift ids translate user/group ids before performing operations in the lower filesystem were translating them into init_user_ns, whereas they should have been translated into the s_user_ns for the lower filesystem. This resulted in using ids other than the intended ones in the lower fs, which likely did not map into the shifts s_user_ns. A local attacker could use this to possibly bypass discretionary access control permissions.
Byobu Apport hook may disclose sensitive information since it automatically uploads the local user's .screenrc which may contain private hostnames, usernames and passwords. This issue affects: byobu
python-apt only checks the MD5 sums of downloaded files in `Version.fetch_binary()` and `Version.fetch_source()` of apt/package.py in version 1.9.0ubuntu1 and earlier. This allows a man-in-the-middle attack which could potentially be used to install altered packages and has been fixed in versions 1.9.0ubuntu1.2, 1.6.5ubuntu0.1, 1.1.0~beta1ubuntu0.16.04.7, 0.9.3.5ubuntu3+esm2, and 0.8.3ubuntu7.5.
Python-apt doesn't check if hashes are signed in `Version.fetch_binary()` and `Version.fetch_source()` of apt/package.py or in `_fetch_archives()` of apt/cache.py in version 1.9.3ubuntu2 and earlier. This allows downloads from unsigned repositories which shouldn't be allowed and has been fixed in verisions 1.9.5, 1.9.0ubuntu1.2, 1.6.5ubuntu0.1, 1.1.0~beta1ubuntu0.16.04.7, 0.9.3.5ubuntu3+esm2, and 0.8.3ubuntu7.5.