gnome-shell 3.22 through 3.24.1 mishandles extensions that fail to reload, which can lead to leaving extensions enabled in the lock screen. With these extensions, a bystander could launch applications (but not interact with them), see information from the extensions (e.g., what applications you have opened or what music you were playing), or even execute arbitrary commands. It all depends on what extensions a user has enabled. The problem is caused by lack of exception handling in js/ui/extensionSystem.js.
GNOME Shell 3.14.x before 3.14.1, when the Screen Lock feature is used, does not limit the aggregate memory consumption of all active PrtSc requests, which allows physically proximate attackers to execute arbitrary commands on an unattended workstation by making many PrtSc requests and leveraging a temporary lock outage, and the resulting temporary shell availability, caused by the Linux kernel OOM killer.
A locking protection bypass flaw was found in some versions of gnome-shell as shipped within CentOS Stream 8, when the "Application menu" or "Window list" GNOME extensions are enabled. This flaw allows a physical attacker who has access to a locked system to kill existing applications and start new ones as the locked user, even if the session is still locked.
Linux distributions using CAPSYSNICE for gnome-shell may be exposed to a privilege escalation issue. An attacker, with low privilege permissions, may take advantage of the way CAPSYSNICE is currently implemented and eventually load code to increase its process scheduler priority leading to possible DoS of other services running in the same machine.
An issue was discovered in certain configurations of GNOME gnome-shell through 3.36.4. When logging out of an account, the password box from the login dialog reappears with the password still visible. If the user had decided to have the password shown in cleartext at login time, it is then visible for a brief moment upon a logout. (If the password were never shown in cleartext, only the password length is revealed.)