IPFire < v2.29 Stored XSS via Mail Server Settings

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 txt_mailuser and txt_mailpass parameters when updating the mail server settings. When a user updates the mail server, the application issues an HTTP POST request to /cgi-bin/mail.cgi and the username and password are provided in the txt_mailuser and txt_mailpass parameters. 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 the affected mail configuration.