https://nvd.nist.gov/vuln/detail/CVE-2017-15908 says this is a infinite loop DoS...

the_why_of_y on Dec 28, 2019 | parent | context | favorite | on: Debian votes for Proposal B, “Systemd but we suppo...

https://nvd.nist.gov/vuln/detail/CVE-2017-15908 says this is a infinite loop DoS in systemd-resolved, so it can't be the (hypothetical) bug described by the GP since it's neither a RCE nor in systemd PID1.