In Ubuntu, gnome-control-center did not properly reflect SSH remote login status when the system was configured to use systemd socket activation for openssh-server. This could unknowingly leave the local machine exposed to remote SSH access contrary to expectation of the user.
Running DDoS on tcp port 22 will trigger a kernel crash. This issue is introduced by the backport of a commit regarding nft_lookup without the subsequent fixes that were introduced after this commit. The resolution of this CVE introduces those commits to the linux-bluefield package.
A flaw was found in the OpenSSH package. For each ping packet the SSH server receives, a pong packet is allocated in a memory buffer and stored in a queue of packages. It is only freed when the server/client key exchange has finished. A malicious client may keep sending such packages, leading to an uncontrolled increase in memory consumption on the server side. Consequently, the server may become unavailable, resulting in a denial of service attack.
An authenticated user who has read access to the juju controller model, may construct a remote request to download an arbitrary file from the controller's filesystem.
Mark Laing discovered in LXD's PKI mode, until version 5.21.1, that a restricted certificate could be added to the trust store with its restrictions not honoured.