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.
https://github.com/systemd/systemd/security/advisories/GHSA-gx6q-6f99-m764
https://github.com/systemd/systemd/commit/efa6ba2ab625aaa160ac435a09e6482fc63bdbe8
https://github.com/systemd/systemd/commit/b5fd14693057e5f2c9b4a49603be64ec3608ff6c
https://github.com/systemd/systemd/commit/80acea4ef80a4bb78560ed970c34952299b890d6
https://github.com/systemd/systemd/commit/7ac3220213690e8a8d6d2a6e81e43bd1dce01d69
https://github.com/systemd/systemd/commit/54588d2dedff54bfb6036670820650e4ea74628f
https://github.com/systemd/systemd/commit/42aee39107fbdd7db1ccd402a2151822b2805e9f
https://github.com/systemd/systemd/commit/3cee294fe8cf4fa0eff933ab21416d099942cabd
https://github.com/systemd/systemd/commit/21167006574d6b83813c7596759b474f56562412
https://github.com/systemd/systemd/commit/20021e7686426052e3a7505425d7e12085feb2a6
https://github.com/systemd/systemd/commit/1d22f706bd04f45f8422e17fbde3f56ece17758a