according to
https://lists.suse.com/pipermail/sle-security-updates/2023-August/015810.html 
there should be a security update for gstreamer-plugins-bad on openSUSE Leap
15.5. However no such update is found:

# zypper in -t patch SUSE-2023-3249=1
Retrieving repository 'Update repository with debuginfo for updates from SUSE
Linux Enterpris[done]
Building repository 'Update repository with debuginfo for updates from SUSE
Linux Enterprise [done]
Retrieving repository 'Update repository with updates from SUSE Linux
Enterprise 15' metadata[done]
Building repository 'Update repository with updates from SUSE Linux Enterprise
15' cache ....[done]
Loading repository data...
Reading installed packages...
'SUSE-2023-3249=1' not found in package names. Trying capabilities.
No provider of 'SUSE-2023-3249=1' found.
Resolving package dependencies...
Nothing to do.

I checked http://download.opensuse.org/update/leap/15.5/sle/x86_64/ 1 but could
not find the recommended version gstreamer-plugins-bad-1.22.0-150500.3.3.1.
There are packages for other gstreamer packages like gstreamer-plugins-base,
but not for gstreamer-plugins-bad. These other gstreamer packages have been
successfully updated on my system while I have version 1.22.0-lp155.2.8 for
gstreamer-plugins-bad.