It was discovered that the gnome-shell lock screen since version 3.15.91 did not properly restrict all contextual actions. An attacker with physical access to a locked workstation could invoke certain keyboard shortcuts, and potentially other actions.
https://gitlab.gnome.org/GNOME/gnome-shell/issues/851
https://bugzilla.redhat.com/show_bug.cgi?id=CVE-2019-3820
https://usn.ubuntu.com/3966-1/
http://lists.opensuse.org/opensuse-security-announce/2019-06/msg00023.html
http://lists.opensuse.org/opensuse-security-announce/2019-06/msg00049.html
Source: MITRE
Published: 2019-02-06
Updated: 2021-09-29
Type: CWE-287
Base Score: 4.6
Vector: AV:L/AC:L/Au:N/C:P/I:P/A:P
Impact Score: 6.4
Exploitability Score: 3.9
Severity: MEDIUM
Base Score: 4.3
Vector: CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L
Impact Score: 3.4
Exploitability Score: 0.9
Severity: MEDIUM