Concrete CMS below version 9.5.3 is vulnerable to Stored XSS via country-less Address attribute in Express association views

In Concrete CMS below version 9.5.3, the Address attribute's country-less text formatter skipped HTML-escaping, enabling stored XSS in Express association views. A user able to submit an Address attribute could execute script in the session of any dashboard user who opened the affected entry. The unescaped branch was reachable because a non-required Address attribute accepted a blank country, and because several Express association templates (for example concrete/elements/express/form/view/dashboard/association.php) echoed the association label mask without applying h(). The Concrete CMS security team gave this vulnerability a CVSS v4.0 score of 7.5 with vector CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N. Thanks Yonatan Drori from Tenzai for reporting.