library/DBTech/Security/Action/Sessions.php in DragonByte vBSecurity 3.x through 3.3.0 for vBulletin 3 and vBulletin 4 allows self-XSS via $session['user_agent'] in the "Login Sessions" feature.
Exploit prediction scoring system (EPSS) score
EPSS Score 0.003
EPSS Ranking 53.0%