IPFire versions prior to 2.29 (Core Update 198) contain a stored cross-site scripting (XSS) vulnerability that allows an authenticated attacker to inject arbitrary JavaScript code through the QUOTA_USERS parameter when creating a user quota rule. When a user adds a new user quota rule the application issues an HTTP POST request to /cgi-bin/urlfilter.cgi with the MODE parameter set to USERQUOTA and the assigned user(s) provided in the QUOTA_USERS parameter. The value of this parameter is stored a