A flaw was found in the Linux kernel. A use-after-free was found in the way the console subsystem was using ioctls KDGKBSENT and KDSKBSENT. A local user could use this flaw to get read memory access out of bounds. The highest threat from this vulnerability is to data confidentiality.
https://www.starwindsoftware.com/security/sw-20210325-0006/
https://lkml.org/lkml/2020/10/29/528
https://lkml.org/lkml/2020/10/16/84
https://lists.debian.org/debian-lts-announce/2020/12/msg00027.html
https://lists.debian.org/debian-lts-announce/2020/12/msg00015.html