There seems to be a problem with appimages including electron on Ubuntu 24.04. When starting cursor (0.45.8), you get error messages like this:

feb 06 11:37:24 gamma kernel: audit: type=1400 audit(1738838244.309:315): apparmor="AUDIT" operation="userns_create" class="namespace" info="Userns create - transitioning profile" profile="unconfined" pid=28305 comm="cursor" requested="userns_create" target="unprivileged_userns"
feb 06 11:37:24 gamma kernel: audit: type=1400 audit(1738838244.310:316): apparmor="DENIED" operation="capable" class="cap" profile="unprivileged_userns" pid=28316 comm="cursor" capability=21  capname="sys_admin"
feb 06 11:37:24 gamma /usr/libexec/gdm-x-session[28305]: [28305:0206/113724.318413:FATAL:setuid_sandbox_host.cc(163)] The SUID sandbox helper binary was found, but is not configured correctly. Rather than run without sandboxing I'm aborting now. You need to make sure that /tmp/.mount_cursorbCLhGT/chrome-sandbox is owned by root and has mode 4755.
feb 06 11:37:24 gamma kernel: traps: cursor[28305] trap int3 ip:5d79fb77726c sp:7fffe2cdbd60 error:0 in cursor[5d79f77ea000+8974000]
feb 06 11:37:24 gamma /usr/libexec/gdm-x-session[28304]: Trace/breakpoint trap (core dumped)
feb 06 11:37:24 gamma systemd[1]: tmp-.mount_cursorbCLhGT.mount: Deactivated successfully.

To get around this, I created /etc/apparmor.d/cursor with this content:

abi <abi/4.0>,
include <tunables/global>

profile cursor /usr/bin/cursor flags=(unconfined) {
    userns,

    # Site-specific additions and overrides. See local/README for details.
    include if exists <local/cursor>
}

Note that I renamed the appimage file to /usr/bin/cursor, and chmod +x it.

After reloading the apparmor configuration with

sudo apparmor_parser -r /etc/apparmor.d/cursor

I could start cursor properly.