Despite being a security critical component, systemd doesn't even seem to have a proper security announcement release process. For example, there was a remote code execution vuln discovered in their DHCP client in October (CVE-2018-15688).[1] The issue was fixed with a GitHub PR that failed to mention that the changes fix a remote exec vulnerability: https://github.com/systemd/systemd/pull/10518
They also have a rather informal release process. Their "release notes" are just a very long NEWS file[2] in the git repo, with notes of trivial and critical changes mishmashed together. And for some reason, to this date there is not a mention of the DHCP remote exec vuln fixed in the latest release.
I must say I don't feel too good about this project's attitude towards security. Compare this to e.g. Apache.
[1] https://www.theregister.co.uk/2018/10/26/systemd_dhcpv6_rce/