Vvveb < 1.0.8.3 Stored XSS via Signup Controller

Vvveb before 1.0.8.3 contains a stored cross-site scripting vulnerability in the customer signup flow where the Signup::addUser() controller copies raw POST username values into the display_name field before sanitization occurs. Attackers can submit HTML and script markup in the username field during signup, which gets stripped from the username column but persisted verbatim in the display_name column, allowing stored XSS execution when display_name is rendered without encoding in vulnerable views.