An issue was discovered in phpList through 3.5.4. An error-based SQL Injection vulnerability exists via the Import Administrators section.
https://www.phplist.org/newslist/phplist-3-5-5-release-notes/
https://discuss.phplist.org/t/phplist-3-5-5-has-been-released/6377
https://blog.telspace.co.za/2020/07/phplist-cve-2020-15072-cve-2020-15073.html