When the screen is locked, you can freeze the screensaver application by holding escape and scrolling up to activate the unlock screen with the mouse. 'authentication error' pops up and the password input {widget?} is non-responsive.
this isn't likely to pose a problem, but I will poke at it a bit and if I see an issue with commands running with the user's privilege I will let you know.
ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: gnome-screensaver 3.6.1-8ubuntu3
ProcVersionSignature: Ubuntu 4.15.0-112.113-generic 4.15.18
Uname: Linux 4.15.0-112-generic x86_64
ApportVersion: 2.20.9-0ubuntu7.16
Architecture: amd64
CurrentDesktop: ubuntu:GNOME
Date: Sun Aug 23 13:14:59 2020
InstallationDate: Installed on 2019-07-05 (415 days ago)
InstallationMedia: Ubuntu 18.04 LTS "Bionic Beaver" - Release amd64 (20180426)
ProcEnviron:
PATH=(custom, no user)
XDG_RUNTIME_DIR=<set>
LANG=en_US.UTF-8
SHELL=/bin/bash
SourcePackage: gnome-screensaver
UpgradeStatus: No upgrade log present (probably fresh install)
Thank you for your bug report, could you take a photo showing the issue? What desktop do you use? The component you reported against is a legacy and not used in the default Ubuntu Desktop