IPFire < v2.29 Stored XSS via Location Group 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 into the COUNTRY_CODE parameter when creating a location group. When a user adds a new location group, the application issues an HTTP POST request with the ACTION parameter set to savelocationgrp, and the value of the COUNTRY_CODE parameter determines the flag displayed for that group. The value of this parameter is stored and later rendered in the web interface without proper sanitization or encoding, allowing malicious scripts to be executed in the context of other users viewing the affected page.