A new release of the Ubuntu Cloud Images for stable Ubuntu release 16.04 LTS (Xenial Xerus) is available at [1]. These new images superseded the existing images [2]. Images are available for download or immediate use on EC2 via publish AMI ids. Users who wish to update their existing installations can do so with:
   'sudo apt-get update && sudo apt-get dist-upgrade && sudo reboot'.

The following packages have been updated. Please see the full changelogs
for a complete listing of changes:
 * dnsmasq: 2.75-1ubuntu0.16.04.7 => 2.75-1ubuntu0.16.04.8 
 * git: 1:2.7.4-0ubuntu1.9 => 1:2.7.4-0ubuntu1.10 
 * glib2.0: 2.48.2-0ubuntu4.6 => 2.48.2-0ubuntu4.8 
 * linux-meta: 4.4.0.203.209 => 4.4.0.204.210 
 * linux-signed: 4.4.0-203.235 => 4.4.0-204.236 
 * python3.5: 3.5.2-2ubuntu0~16.04.12 => 3.5.2-2ubuntu0~16.04.13 
 * screen: 4.3.1-2build1 => 4.3.1-2ubuntu0.1 


The following is a complete changelog for this image.
new: {'linux-modules-4.4.0-204-generic': '4.4.0-204.236', 'linux-headers-4.4.0-204-generic': '4.4.0-204.236', 'linux-headers-4.4.0-204': '4.4.0-204.236'}
removed: {'linux-headers-4.4.0-203': '4.4.0-203.235', 'linux-modules-4.4.0-203-generic': '4.4.0-203.235', 'linux-headers-4.4.0-203-generic': '4.4.0-203.235'}
changed: ['dnsmasq-base', 'git', 'git-man', 'libglib2.0-0:amd64', 'libglib2.0-data', 'libpython3.5-minimal:amd64', 'libpython3.5-stdlib:amd64', 'libpython3.5:amd64', 'linux-headers-generic', 'linux-headers-virtual', 'linux-image-4.4.0-204-generic', 'linux-image-virtual', 'linux-virtual', 'python3.5', 'python3.5-minimal', 'screen']
new snaps: {}
removed snaps: {}
changed snaps: []
==== dnsmasq: 2.75-1ubuntu0.16.04.7 => 2.75-1ubuntu0.16.04.8 ====
====     dnsmasq-base
  * SECURITY REGRESSION: issue with multiple queries (LP: #1916462)
    - backport multiple upstream commits to fix regressions
      + 04490bf622ac84891aad6f2dd2edf83725decdee
      + 12af2b171de0d678d98583e2190789e544440e02
      + 3f535da79e7a42104543ef5c7b5fa2bed819a78b
      + 141a26f979b4bc959d8e866a295e24f8cf456920
      + 305cb79c5754d5554729b18a2c06fe7ce699687a
==== git: 1:2.7.4-0ubuntu1.9 => 1:2.7.4-0ubuntu1.10 ====
====     git git-man
  * SECURITY UPDATE: remote code exec during clone on case-insensitive FS
    - debian/patches/CVE-2021-21300.patch: fix bug that makes checkout
      follow symlinks in leading path in cache.h, compat/mingw.c,
      git-compat-util.h, run-command.c, symlinks.c, t/t0021-conversion.sh,
      t/t2006-checkout-index-basic.sh, unpack-trees.c.
    - CVE-2021-21300
==== glib2.0: 2.48.2-0ubuntu4.6 => 2.48.2-0ubuntu4.8 ====
====     libglib2.0-0:amd64 libglib2.0-data
  * SECURITY UPDATE: incorrect g_file_replace() symlink handling
    - debian/patches/CVE-2021-28153-pre1.patch: allow g_test_bug() to be
      used without g_test_bug_base() in /glib/gtestutils.c.
    - debian/patches/CVE-2021-28153-1.patch: fix a typo in a comment in
      gio/glocalfileoutputstream.c.
    - debian/patches/CVE-2021-28153-2.patch: stop using g_test_bug_base()
      in file tests in gio/tests/file.c.
    - debian/patches/CVE-2021-28153-3.patch: factor out a flag check in
      gio/glocalfileoutputstream.c.
    - debian/patches/CVE-2021-28153-4.patch: fix CREATE_REPLACE_DESTINATION
      with symlinks in gio/glocalfileoutputstream.c, gio/tests/file.c.
    - debian/patches/CVE-2021-28153-5.patch: add a missing O_CLOEXEC flag
      to replace() in gio/glocalfileoutputstream.c.
    - CVE-2021-28153
  * SECURITY UPDATE: g_byte_array_new_take length truncation
    - debian/patches/CVE-2021-2721x/CVE-2021-27218.patch: do not accept too
      large byte arrays in glib/garray.c, glib/gbytes.c,
      glib/tests/bytes.c.
    - CVE-2021-27218
  * SECURITY UPDATE: integer overflow in g_bytes_new
    - debian/patches/CVE-2021-2721x/CVE-2021-27219*.patch: add internal
      g_memdup2() function and use it instead of g_memdup() in a bunch of
      places.
    - CVE-2021-27219
==== linux-meta: 4.4.0.203.209 => 4.4.0.204.210 ====
====     linux-headers-generic linux-headers-virtual linux-image-virtual linux-virtual
  * Bump ABI 4.4.0-204
==== linux-signed: 4.4.0-203.235 => 4.4.0-204.236 ====
====     linux-image-4.4.0-204-generic
  * Master version: 4.4.0-204.236
==== python3.5: 3.5.2-2ubuntu0~16.04.12 => 3.5.2-2ubuntu0~16.04.13 ====
====     libpython3.5-minimal:amd64 libpython3.5-stdlib:amd64 libpython3.5:amd64 python3.5 python3.5-minimal
  * SECURITY UPDATE: Code execution from content received via HTTP
    - debian/patches/CVE-2020-27619.patch: no longer call eval() on
      content received via HTTP in Lib/test/multibytecodec_support.py.
    - CVE-2020-27619
  * SECURITY UPDATE: Buffer overflow
    - debian/patches/CVE-2021-3177.patch: replace snprintf with Python unicode
      formatting in ctypes param reprs in Lib/ctypes/test/test_parameters.py,
      Modules/_ctypes/callproc.c.
    - CVE-2021-3177
==== screen: 4.3.1-2build1 => 4.3.1-2ubuntu0.1 ====
====     screen
  * SECURITY UPDATE: DoS via crafted UTF-8 character sequence
    - debian/patches/99_CVE-2021-26937.patch: fix out of bounds array
      access in encoding.c.
    - CVE-2021-26937

--
[1] http://cloud-images.ubuntu.com/releases/xenial/release-20210316/
[2] http://cloud-images.ubuntu.com/releases/xenial/release-20210224/