CVE-2026-70371: Koha: SQL Injection in reports/issues_avg_stats.pl

Koha's reports/issuesavgstats.pl builds dynamic SQL in sub calculate by concatenating several user-controlled request parameters directly into the query string. The Line and Column parameters are not validated against any whitelist and land verbatim in identifier positions (SELECT DISTINCTROW, GROUP BY, ORDER BY), and each Filter slot is concatenated raw into single-quoted LIKE, BETWEEN, and comparison fragments with no bound parameters. 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), apikeys, and sessions.