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 SERVICE, LOGIN, and PASSWORD parameters when creating or editing a Dynamic DNS host. When a new Dynamic DNS host is added, the application issues an HTTP POST request to /cgi-bin/ddns.cgi and saves the values of the LOGIN, PASSWORD, and SERVICE parameters. The SERVICE value is displayed after the host entry is created, and the LOGIN and PASSWORD values are displayed when that host entry is edited. The values of these parameters are stored and later rendered in the web interface without proper sanitation or encoding, allowing injected scripts to execute in the context of other users who view or edit the affected Dynamic DNS entries.