HTML::FormHandler versions before 0.410002 for Perl render some error messages into HTML without escaping.
The Table form layout and the Bootstrap 2 and 3 wrappers splice each error string straight into the surrounding markup. Version 0.410000, the fix for CVE-2026-19872, escaped the equivalent values in the other layouts and wrappers, and 0.410002 extended that to these three.
Error messages that contain attacker-influenced content such as rejected field values could embed JavaScript in rendered pages.
