Koha's guided report builder (reports/guided_reports.pl) reads the CGI parameter and, for each value, a dynamically-named parameter, and concatenates both directly into an SQL ORDER BY clause with no allowlist or validation. Since ORDER BY columns cannot be bound via prepared-statement placeholders, this requires an explicit allowlist, which does not exist.
https://github.com/Koha-Community/Koha/blob/master/reports/guided_reports.pl