Affected: regularlabs.com Quick Index (Free, Pro) extension for Joomla

Joomla Extension - regularlabs.com - Privileged stored XSS via class option in Quick Index extension for Joomla < 5.0.5 - Quick Index inserts configurable class values into generated HTML without escaping them for an HTML attribute. A crafted value can close the intended class attribute and introduce a new attribute. Joomla's content filter cannot reliably prevent this because Quick Index creates the executable HTML after the authored plugin syntax was filtered.