A heap use-after-free vulnerability was found in systemd before version v245-rc1, where asynchronous Polkit queries are performed while handling dbus messages. A local unprivileged attacker can abuse this flaw to crash systemd services or potentially execute code and elevate their privileges, by sending specially crafted dbus messages.
https://www.openwall.com/lists/oss-security/2020/02/05/1
https://lists.debian.org/debian-lts-announce/2022/06/msg00025.html
https://github.com/systemd/systemd/commit/ea0d0ede03c6f18dbc5036c5e9cccf97e415ccc2
https://github.com/systemd/systemd/commit/bc130b6858327b382b07b3985cf48e2aa9016b2d
https://github.com/systemd/systemd/commit/637486261528e8aa3da9f26a4487dc254f4b7abb
https://github.com/systemd/systemd/commit/1068447e6954dc6ce52f099ed174c442cb89ed54