IPFire < v2.29 Stored XSS via Whitelisted Host Creation

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 IGNORE_ENTRY_REMARK parameter when adding a whitelisted host. When a whitelisted host is added, an HTTP POST request is sent to the Request-URI /cgi-bin/ids.cgi and the remark for the entry is provided in the IGNORE_ENTRY_REMARK parameter. The value of this parameter is stored and later rendered in the web interface without proper sanitization or encoding, allowing injected scripts to execute in the context of other users who view the affected whitelist entry.