The way the Referer header in article.php is handled in Chadha PHPKB Standard Multi-Language 9 allows attackers to execute Stored (Blind) XSS (injecting arbitrary web script or HTML) in admin/report-referrers.php (vulnerable file admin/include/functions-articles.php).
https://antoniocannito.it/phpkb1#blind-cross-site-scripting-cve-2020-10388