A new release of the Ubuntu Cloud Images for stable Ubuntu release 21.04 (Hirsute Hippo) 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 These new images superseded the existing images [2].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:
 * ca-certificates: 20210119build1 => 20210119ubuntu0.21.04.1 
 * linux-meta: 5.11.0.36.38 => 5.11.0.37.39 
 * linux-signed: 5.11.0-36.40 => 5.11.0-37.41 
 * netplan.io: 0.102-0ubuntu3 => 0.103-0ubuntu5~21.04.1 
 * ubuntu-release-upgrader: 1:21.04.16 => 1:21.04.17 


The following is a complete changelog for this image.
new: {'linux-headers-5.11.0-37-generic': '5.11.0-37.41', 'linux-modules-5.11.0-37-generic': '5.11.0-37.41', 'linux-headers-5.11.0-37': '5.11.0-37.41'}
removed: {'linux-headers-5.11.0-36': '5.11.0-36.40', 'linux-modules-5.11.0-36-generic': '5.11.0-36.40', 'linux-headers-5.11.0-36-generic': '5.11.0-36.40'}
changed: ['ca-certificates', 'libnetplan0:amd64', 'linux-headers-generic', 'linux-headers-virtual', 'linux-image-5.11.0-37-generic', 'linux-image-virtual', 'linux-virtual', 'netplan.io', 'python3-distupgrade', 'ubuntu-release-upgrader-core']
new snaps: {}
removed snaps: {}
changed snaps: ['snapd']
==== ca-certificates: 20210119build1 => 20210119ubuntu0.21.04.1 ====
====     ca-certificates
  [ Dimitri John Ledkov ]
  * mozilla/blacklist.txt: blacklist expired "DST Root CA X3".
    (LP: #1944481)
==== linux-meta: 5.11.0.36.38 => 5.11.0.37.39 ====
====     linux-headers-generic linux-headers-virtual linux-image-virtual linux-virtual
  * Bump ABI 5.11.0-37
  * Packaging resync (LP: #1786013)
    - [Packaging] resync debian/dkms-versions from main package
==== linux-signed: 5.11.0-36.40 => 5.11.0-37.41 ====
====     linux-image-5.11.0-37-generic
  * Master version: 5.11.0-37.41
==== netplan.io: 0.102-0ubuntu3 => 0.103-0ubuntu5~21.04.1 ====
====     libnetplan0:amd64 netplan.io
  * Backport netplan.io 0.103-0ubuntu5 to 21.04 (LP: #1938920)
    - Add YAML generator and Keyfile parser for NetworkManager YAML backend
    - Add activation-mode parameter
    - Add io.netplan.Netplan.Generate() DBus method
    - Changed the way of how unmanaged-devices are handled by NetworkManager
  * Add d/p/0003-Mute-gateway4-6-deprecation-warnings.patch:
    - Do not show a deprecation warning on the backported version
  * Update systemd dependency to >= 247.3-3ubuntu3.2 for activation-mode
  * Update debian/gbp.conf
  * Use debhelper-compat 12 in debian/control
  * Keep skipping many armhf/LXD tests
  * Skip flaky 'regressions' test on armhf/LXD containers, too
==== ubuntu-release-upgrader: 1:21.04.16 => 1:21.04.17 ====
====     python3-distupgrade ubuntu-release-upgrader-core
  * DistUpgrade/DistUpgradeFetcherCore.py: when running in non-interactive
    mode do not show the release notes. (LP: #1944475)
  * Run pre-build.sh: updating mirrors, demotions, and translations.

--
[1] http://cloud-images.ubuntu.com/releases/hirsute/release-20210928/
[2] http://cloud-images.ubuntu.com/releases/hirsute/release-20210922/