Privoce Vocechat Query Parameter widget.html cross site scripting

A vulnerability has been found in Privoce Vocechat up to 0.9.121. This issue affects some unknown processing of the file widget.html of the component Query Parameter Handler. Such manipulation of the argument welcome leads to cross site scripting. The attack can be launched remotely. The exploit has been disclosed to the public and may be used. The vendor was contacted early about this disclosure but did not respond in any way.