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 PROT parameter when creating a new service. When a user adds a service, the application issues an HTTP POST request with the ACTION parameter set to saveservice, and the protocol type is specified in the PROT 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 viewing the affected service entry.