In udev in systemd before 260, local root execution can occur via malicious hardware devices and unsanitized kernel output.

In nspawn in systemd 233 through 259 before 260, an escape-to-host action can occur via a crafted optional config file.

systemd, a system and service manager, (as PID 1) hits an assert and freezes execution when an unprivileged IPC API call is made with spurious data. On version v249 and older the effect is not an assert, but stack overwriting, with the attacker controlled content. From version v250 and newer this is not possible as the safety check causes an assert instead. This IPC call was added in v239, so versions older than that are not affected. Versions 260-rc1, 259.2, 258.5, and 257.11 contain patches. No known workarounds are available.

In systemd 258 before 260, a local unprivileged user can trigger an assert when a Delegate=yes and User=<unset> unit exists and is running.