IPFire < v2.29 Stored XSS via DNS Creation (dns.cgi)

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 TLS_HOSTNAME parameter when adding a new DNS entry. When a user adds a DNS entry, the application issues an HTTP POST request to /cgi-bin/dns.cgi and the TLS hostname is provided in the TLS_HOSTNAME parameter. The value of this parameter is 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 DNS configuration.