Koha's reports/issues_stats.pl (the circulation statistics report) builds its calculation query in sub calculate by concatenating several user-controlled request parameters directly into the SQL string. The PeriodTypeSel, PeriodDaySel, and PeriodMonthSel parameters are interpolated raw into single-quoted equality and function-comparison fragments, and the Filter slots plus the Line and Column identifiers are likewise interpolated with no whitelist and no placeholder binding. An authenticated staff user holding the reports module permission can inject arbitrary SQL and read any table reachable by the Koha database user, including borrowers (password hashes, two-factor secrets, personal data), api_keys, and sessions.